2 4 0 T U R B O . C O M
 
Volvo Limited Slip and Locking
Rear End Options


     UPDATED: May 18, 2022                       CONTACT       
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G80 in a 240
G80 Mods
Diff Sensors
Other Misc Rear End Stuff

240 Trans, Rear End Ratios for USA and Canada
Info taken from Volvo "New Car Features" Greenbooks and Owner's Manuals. Some anomalies are certainly possible..
YEAR
Specification
Auto Trans
Manual Trans
1975
B20F D-Jet (242, 244)
4.10 BW35
4.10 M40, M41
1975
B20F D-Jet (245)
4.30 BW35
4.30 M40, M41
1976
B21F K-Jet
3.91 BW55
3.91 with M45
1976
B21F K-Jet
3.91 BW55
4.10 with M46
1976
B21F K-Jet  California
4.10 BW55
4.10 M45, M46
1977
B21F K-Jet
3.91 AW55, BW55
3.91 M45, M46
1978
B21F K-Jet
3.91 AW55 (245 BW55)
3.91 M45, M46
1978
B21A Carb  Canada
3.91 BW55
3.91 M45, M46
1979
B21F K-Jet
3.73 AW55
3.91 M45, M46
1979
B21A Carb  Canada
3.73 BW55
3.91 M45, M46
1980
B21F K-Jet
3.73 AW55 (245 BW55)
3.91 M45, M46
1980
B21A Carb Canada
3.73 BW55
3.91 M45, M46
1981
B21F K-Jet
3.73 AW55 (245 BW55)
3.73 M45, M46
1981
B21F-MPG K-Jet
3.54 AW55
3.54 M46
1981
B21A Carb, B23E  Canada
3.73 BW55
3.91 M45, M46
1981
B23E K-Jet  Canada
3.54 BW55
3.73 M45, M46
1981
B21F GLT
N/A
3.91 M46
1981
B21FT Turbo
N/A
3.73 M46
1981
D24 Diesel
3.31 BW55
3.54 M46
1981
D24 Diesel  Canada
3.54 BW55
3.73 M46
1982
B21A Carb  Canada
3.54 BW55 3.54 M45, M46
1982
B23E K-Jet  Canada
3.54 BW55
3.73 M46
1982
B21F K-Jet or LH EFI
3.91 AW70
3.54 M46
1982
B21FT Turbo
3.73 AW71
3.73 M46
1982
D24 Diesel
3.31 BW55
3.54 M46
1983
B21A Carb Canada
3.54 BW55 3.54 M46
1983
B23E K-Jet Canada
3.54 BW55
3.73 M46
1983
B21FT Turbo
3.91 AW71
3.73 M46
1983
B23F-LH
3.73 AW70
3.31 M46
1983
D24 Diesel
3.31 BW55
3.54 M46
1984
B21FT Turbo
3.91 AW71
3.73 M46
1984
B23F-LH
3.73 AW70
3.31 M46
1984
D24 Diesel
3.31 BW55
3.54 M46
1985
B230F LH 2.2
3.73 AW70
3.31 M46
1985
B21FT Turbo
3.91 AW71
3.73 M46
1985
D24 Diesel
3.31 BW55
3.54 M46
1986
B230F LH 2.2
3.73 AW70
3.31 M46
1987
B230F LH 2.2
3.73 AW70
3.31 M47
1988
B230F LH 2.2
3.73 AW70
3.31 M47
1989
B230F LH 2.4
3.73 AW70
3.31 M47
1990
B230F LH 2.4
3.73 AW70
3.31 M47
1991
B230F LH 2.4
3.73 AW70
3.31 M47
1992
B230F LH 2.4
3.73 AW70
3.31 M47
1993
B230F LH 2.4
3.73 AW70
3.31 M47


Installing a G80 Locking Differential
(pulled from a 700 / 900 series)
into your 240

The G80 Automatic Locking Differential is a special differential that Volvo began putting in 740/940/960 models beginning in late 1991 as standard equipment in NORTH AMERICAN market cars. It was also made available as a factory option for the 240 in 1993. Volvo referred to it as the Automatic Locking Differential (A.L.D.). 

Not all 1991 700/900 models got a G80, but it you're looking, it should for certain be found in all 1992 and later 700/900 Volvos (North American market). 

The G80 differential was manufactured by Eaton and was designed to provide positive locking of the rear wheels during low speeds if extra traction becomes needed, typically below 25 mph (40 km/h).  The differential initially acts as an open differential until it senses a speed difference between the axles. It then locks to provide traction to both wheels. As speed increases, the differential can sense the speed increase and it then unlocks at speeds above 25 mph.  It does this by using a centrifugal weight which changes position as speed increases.

Here are some videos from Eaton explaining how this differential works:
https://www.youtube.com/watch?v=tTGZOJQQBeE


https://www.youtube.com/watch?v=ftyJvIO0DZ8


G80 LUBRICANT WARNING
DO NOT put any lubricant in a G80 differential that has Limited Slip additives or LSD friction modifiers.
GM recommends GL-5 rated lubricant, but be sure to check the label. Some GL-5 lubes have LSD additives.

If the oil label says it's for "CONVENTIONAL" differentials or for "OPEN or LOCKING" differentials, then it's OK. 
An appropriate lube weight is 75W90. Heavier weights or synthetic lubricants may also be used as long it is rated GL-5 or for CONVENTIONAL or OPEN differentials. 
A G80 differential has friction plates similar to a Limited Slip differential, but they are made of metal instead of normal LSD clutch friction material. Adding any Limited Slip friction modifiers to a G80 will prevent the friction plates from properly gripping when they need to.  So if you accidentally added LSD additives and wondered why your G80 converted into one-tire-fire, now you know.
 
LUBE CAPACITY
Volvo 1030: 1.4 US quarts
Volvo 1031: 1.7 US quarts

Visual differences between a Volvo 1030 and 1031 Differential Case. More 1030/1031 info CLICK HERE.

Above photos from Anthony Hyde's Volvo Differential Page

If you intend to install a used G80 differential in a 240, it's a direct (or nearly a direct) bolt-in to any 240 Dana 30 rear end (1030, 1031 and 1041). 
In most cases, the G80 differential will bolt in and run just fine with no adjustments, even without replacement of any bearings or shims.
You MUST remove and reuse your own ring gear, which matches your existing pinion gear, unless you plan to change both of those. Always install those two gears as a matched set. 


If you're concerned about installing a used G80 diff "AS IS," you can take an extra step by also checking the ring gear backlash after installing. This is done using a dial caliper. Backlash is the amount of rotational movement (back and forth) of the ring gear when the pinion gear is stationary. The Volvo specification calls for around .005 to .007 inch (5 to 7 thousands of an inch) of backlash.  There are how-to videos on YouTube for checking ring gear backlash on a rear end.  If the backlash is out of spec, the rear end may whine at some speeds or there may be some unusual wear over time.



CORRECTING EXCESSIVE BACKLASH:
There are shims under the carrier bearings, which can be added or removed. This will adjust the ring gear closer to the pinion gear (which will reduce backlash) or farther from the pinion gear (to increase backlash). Removing bearings and changing shims will of course increase the difficulty of this installation, because these bearings are pressed on.  It can be difficult to remove these bearings without damaging them and some will tell you the quickest removal is cutting them off. I don't think that is necessary.


REMOVING A VOLVO CARRIER BEARING WITH A BEARING PULLER
(Carrier Bearing: AKA Differential Side Bearing)
 
So far I have avoided having to deal with removing or replacing any carrier bearings on two different G80 installations in my 240s. In each case I have simply installed the G80 in my car with the bearings and races that came with the G80 from the donor car. I have not removed the bearings from a donor G80 yet.

If you find yourself needing to change, pull or adjust bearings, here's a little info below that may help.





Reportedly, if you have the correct VOLVO BEARING PULLER TOOL (shown here), then pulling these bearings can allegedly be done without damaging them. 
Without this tool, it is reportedly more difficult to remove these bearings without damage. If you damage them, this means you'll need new bearings.
More information: https://forums.tbforums.com/showthread.php?t=317970&page=2

<<<
I have not personally experienced this MATCO puller tool, but it looks pretty good in the below videos:


Have a look at this video showing a carrier bearing puller made by Matco (Part Number MST4520), which appears to be doing very well on a carrier bearing: 

And here's the OTC version (PN 4520), which looks identical to the Matco:
https://www.youtube.com/watch?v=-eh8WF_ON6g

G80 DIY BOLT-IN INSTALLATION NOTES
There are some people who will tell you that the only "correct" way is to fit the differential just as you would a brand new differential replacement, using new bearings, shims and a professional technician. This, of course, can be VERY expensive and if it's too expensive to try a G80, then there's just no point.
The choice is yours, however many DIY "junkyard" mechanics (myself included) have already done this successfully as (*nearly) a simple bolt-in.
*Regarding the "nearly" a bolt-in thing: The one exception I have found is for 1991 and older 240s. See the info below on trimming the right side axle.


 
See that round silver metal disc below? 

I've seen this plate referred as an "oil slinger" or a "crown wheel screw lock plate" (supposedly to prevent ring bolts from loosening on limited slip differentials). You'll almost never see this plate in a photo of a removed G80 or a retrofitted one, because they're almost never re-used.  That plate is found on all Volvo G80 differentials that were originally installed in Volvos.

This plate covers the ring gear bolts. It will prevent you from removing the ring gear bolts unless the bearing on that side is removed.  


  If you don't plan to remove this bearing and you need that plate gone, you can simply cut the plate off with tin snips and toss it.  This is the method used most often. This way you can swap your ring gear without having to mess with pulling and installing new bearings.
 
(Photo above borrowed from G80 modification article: https://www.turbobricks.com/mods.php?content=art0027)

Here's a YouTube video of someone pulling a G80 from a Volvo at a salvage yard and you can see this disc on that differential:
https://www.youtube.com/watch?v=wwQh9mMtmvE

SALVAGE YARD NOTE: If you remove a G80 from a salvage yard car yourself, make sure you save the bearing races and mark them RIGHT and LEFT with a marker so they end up on the same side as they were installed originally.

BUYING A USED G80

If you're shopping for a used G80, keep in mind that this differential was used in a lot of different cars and trucks. Some have different axle spline counts. 
  The G80 used in Volvo cars was installed in a Dana 30 (1041 axle) with 27 spline axles. All such G80 differentials from a Volvo it will have "VOLVO" and a Volvo part number stamped into it as shown above. The part numbers seem to be pretty various and seem to have changed a number of times over the years.
BEWARE: I have seen that some on-line sellers REMOVE the carrier bearings before selling a Volvo G80. 
So if you want a G80 with the bearings INTACT, be sure to check that before buying.


TRIMMING THE 240 RIGHT SIDE AXLE:
 

This is the part of a G80 installation that makes the difference between nearly a bolt-in or a 100% bolt-in.
If your rear end is from a 1991 or older 240, you will need to trim a small amount off of the inner end of the RIGHT side axle. 
This is because the right axle in that 240 is a bit too long to fit all the way back in with the G80 in place.
The amount that needs to be trimmed is about 1/8 to 1/4 inch. In these photos you can see where I trimmed 1/4 inch off of my right axle. A high-speed cut-off wheel took care of this easily in a few minutes.

LATER 240 AXLE CHANGE:
Sometime in 1992 the 240 axle was changed so that the right side axle was made slightly shorter from the factory. This means that some 1992 and ALL 1993 240 models will not need any axle trimming and this installation will be a 100% bolt-in for these late 240s.
 
740/940 (non-240) Note Worth Mentioning:
The stock axles from a 1041 G80 rear end in a G80 equipped 740 or 940 are a bit shorter (and also fatter) than the stock 1031 axles in a pre-G80 car. Some knowledgeable DIY 700/900 owners have been swapping over both axles from a G80 740/940 when fitting the G80 in their earlier 740s. They fit just fine.
Cutting a right side axle is only for 1991 or older 240 installation.


SENSORS and TONE RINGS
All related to 240s with Electronic Speedometers (1986-93).

19
86 and later 240s came with electronic speedometers which were triggered by a vehicle speed sensor (VSS) in the rear differential cover.
There were two types of VSS: Non-ABS or ABS type.
1986-1992 240 without ABS (below left).
1991-92 240 with optional ABS (below right).
1993 240, ABS was standard (below right).



TONE RINGS
If your G80 came with a 48 tooth tone ring (standard for all ABS equipped Volvos) and your electronic speedo 240 uses a 12 tooth tone ring (standard for NON-ABS 240s), your speedometer will not work correctly.

Some DIY installers have successfully modified the 48 tooth tone ring using a Dremel cut-off wheel to created a 12 tooth ring.
Keep in mind that you should then probably use the sensor that works for the 12 tooth ring.  And if you installed a newer aluminum differential cover from a later car, the earlier sensor might have fitment issues. For such a custom installation, some sensors may be adjustable for depth and some may need shims added or subtracted to adjust depth.
SENSOR DEPTH / CLEARANCE SETTINGS:
12 tooth tone ring: 240 without ABS (1986 to 1992). Should be adjusted to a clearance of 0.85 mm (0.0335 in) +- 0.35 mm. 
48 tooth tone ring: 240 with ABS (optional in 1991-92, standard in 1993). Clearance should be 0.6 mm (0.024 in) +0.2 mm (0.008 in), -0.3 mm (0.012 in). 

Check your clearance with a feeler gauge through the filler hole. Turn the pinion as you do so to check clearance. Start with a thin gauge and go thicker until you can feel the rotating tone ring. 
(Source: https://forums.turbobricks.com/showthread.php?t=204882)

<<< If you need a NEW TONE RING (speed sensor strip) these are available from Kaplhenke Racing.
They are available in 12 tooth or 48 tooth size:  https://www.bneshop.com/collections/240-speed-sensor-strip



Here's a video showing this new tone ring being installed.
https://www.youtube.com/watch?v=H4A1EksTSf0



G80 INTERNAL MODIFICATIONS:
DO YOU REALLY NEED TO MODIFY YOUR G80?
Yours truly has run both a modified one and unmodified one in my 242. I currently have an unmodified one installed and I'm happy with it.  The modified one I used to have was a bit erratic.  It would occasionally lock and unlock the left and right alternately in traction limited settings (drag strip, etc). And occasionally stay locked longer than it should when you no longer needed it locked.  For my street car, I'm much happier with an unmodified G80.
Modifying the G80 is optional. It has been a fairly popular fad among Volvo hot-rodders. A modification is done to the G80 before installing to alter the internal locking mechanism. Altering the internal mechanism can be done to make it stay locked through higher speeds or to even stay locked at all speeds.  But at least one person says, "Even an unmodified G80 will stay locked at much higher speeds than 25 as long as the power is increased. I've had stock units stay locked up until at least 60 mph in turbo cars." (Source: https://forums.tbforums.com/showthread.php?t=240436&page=2 Post #78). 
I agree 100% with this statement and it's what I have found with my unmodified G80.


If you decide you want to modify your G80, this can be done by a couple different methods and these are outlined in the article links below. Not all of the methods are the same, so if this part interests you, read it all.

You can begin by reading this modification tutorial in Turbobricks:
https://www.turbobricks.com/mods.php?content=art0027


More resources below.

Below Video:  Disassembling and Modifying a G80
https://www.youtube.com/watch?v=zXgTWLP_e-I

MORE HELPFUL ARTICLES AND DISCUSSION LINKS:
https://forums.turbobricks.com/showthread.php?t=338768
https://forums.turbobricks.com/showthread.php?t=321262
https://forums.turbobricks.org/showthread.php?p=5136009
http://retrorides.proboards.com/thread/150384/volvo-series-locker-diffs-eaton
http://www.autoevolution.com/news/a-simple-guide-to-the-g80-locking-differential-94874.html
https://www.youtube.com/watch?v=xevx06aay7E
https://forums.turbobricks.com/showthread.php?t=321262



 
Limited Slip Info for Volvo Rear Ends.
This info BELOW was compiled years ago, so some may be out of date.
I have left it up at the request of users for the sake of the info it contains. I hope it helps.

If you need some technical explanation of limited slip differentials, try here:
http://auto.howstuffworks.com/differential.htm and http://en.wikipedia.org/wiki/Limited_slip_differential

The following link goes into greater detail about available LSD's for Volvo rear ends: https://www.turbobricks.com/mods.php?content=art0014


Cutting through all the myths about just what 240's and 740's came with what type of rear end and what Limited Slip or Locker differentials will actually fit these cars has been a long struggle.  The following information below has been submitted and compiled by various experienced Volvonuts over the years and will hopefully help you in making the right decisions. 
Volvo Rear Differential Part Number and Interchange Database:
http://www.nuceng.ca/bill/volvo/database/reardiff.htm

-comment submitted from Justin Wade, dated 2002:
The below Limited Slip Differential info came from Reider Racing and MVP (unfortunately both companies no longer exists). 
It seems the LSDs available are the same for all Dana 1030 and 1031 axle cars, as it's also the same for the "standard" Dana 30 LSD. 
The catch is the gearing cut-off for the particular rear end you have. 
A rear end with gearing of 3.73 and higher will be different internally from one with 3.54 and lower. 

Basically, TracTech (who offers the TrueTrac differential), and Dana only make two limited slip diffs each for the Dana 30 rear end used in 240s and 740s.  One part was designated for all 1030/1031 diffs with 3.54 gears and below, and one part for all 1030/1031 diffs with 3.73 gears and above. 

It just so happens that most 1031s that you will come across will have 3.73:1 gearing or higher because of the high numbers of cars this axle came in -- mostly in turbo cars with mostly auto transmissions, some towing package cars, and seemingly some random 5 speed cars.  One TrueTrac differential for instance, carries a part number of 912A411 for 3.73 and higher cars, regardless of the variation being a 1030 or 1031 axle. 
Of course, if your car came with 3.54 or 3.31 gears, you would require a different part number. 



Dana 30 rear end versions for 240.
Visual differences between a Volvo 1030 and 1031 Differential Case.


The stronger 1031 was introduced in 1981 and originally reserved for 200 series with higher power output, such as 6 cylinder or turbo cars. Eventually all later production 240s would get the 1031.
There is information in Volvo "New Car Feature" Greenbooks that claim the 1030 came in auto trans 240s (including TURBOS) and most manual trans cars were the cars equipped with the 1031. This information has been proven unreliable, since it appears most or all 240 Turbos with auto and manual transmissions received the 1031.
 
According to info in Anthony Hyde's page, late 240s from approximately 1990 to 1993 all received the 1031 rear end, however the later case may have a single rib, adding to confusion.
Tuff240's comment below
suggests that 1986 and later 240s with electric speedometers may all have the 1031 rear end.

Internally, a 1031 will have slightly larger, heavier ring and pinion gears and the pinion shaft is larger in diameter.
A 1030 rear end holds 1.4 U.S. quarts of oil. A 1031 rear end hold 1.7 U.S. quarts.

Above photos and more Dana 30 detail at
Anthony Hyde's Volvo Differential Page

COMMENT 12/08/02: 
Stealthfti  from the Turbobricks Forum wrote:
There are measurable differences between a 1030 and 1031 rear end housing.  A 1030 is about 10.125 inches from the rear cover mounting surface to the front of the pinion neck.  A 1031 is almost exactly 0.5 inches longer.

COMMENT 04/08/02:
Derek Walker wrote that while in the process of examining different options for an LSD for his '89 745 GLE (equipped with a 5.0L Ford engine and 4.10:1 differential), he checked with Reider Racing regarding the Trutrac per the recommendations here.  Reider responded that his 1031 Volvo housing would NOT accept the Trutrac LSD due to slight dimensional differences from the 1030 housing.  It seems they had had a few returns from Volvo owners due to incompatibility issues.  It's not clear if the issues are unique with the Trutrac LSD or the 1031 housing.

Also it does seem all 1031s have the "ears" on the right side of the pumpkin (they are not machined on 240s).  These ears attach to the torque arm on the 740 suspension.  Justin's source for the info on the "ears" and the 1031 axle is Mike Knell, who authored the Volvo V8 swap information in JagsThatRun

From reading posts on 4x4 chat groups, the Trutrac sounds like a great LSD, especially for street performance.  The Dana Powr-Loc (which appears to be the LSD Volvo offered for standard towing packages) is also supposed to be a good, long-lasting differential (although quite expensive when new).

Trutrac Internal Components


UPDATE NOTE 02/12/04: 
tuff240 from the Turbobricks Forum wrote:
The differential units are all the same up until they changed them for the speedo tone ring. The only difference between a 1030 and 1031 is the housing itself and the ring and pinion. The differential units can be swapped back and forth. The ring and pinion cannot.

The later model cars (86 and up), which all have speedo tone rings, are believed to all be 1031's.  A Trutrac unit going in a car that requires a speedo tone ring will be different only to fit the tone ring.  You can still swap tone ring or no tone ring differentials from 1030 to 1031. The only problem will be that you won't have a working speedo if you need a tone ring and install a diff that does not have one.

AGAIN, the major difference is the Ring and Pinion.   The differential units come in 2 sizes depending on what Ring and Pinion you have or want. One will fit 3:73 and up, one will fit below 3:73.  Make sure you pick accordingly in case you ever want to change gears.  For example, you cannot change from a 3:91 ring and pinion to a 3:31 ring and pinion without changing the differential unit. This goes for stock oem diffs and TrueTrac diffs as well.
*EDIT The pinion bearings are also different between a 1030 and 1031. So make sure you get the right pinion bearing for whatever rear end you have.
I abused a 1030 rear end with 200 rwhp for about 15K miles with NO problems whatsoever.  But keep in mind I have no personal experience with 700 series cars, just 200 series cars.


UPDATE NOTE 07/16/06:
-from Matt Dupuis
I installed a Trutrac in my 244 this winter, and would like to share some info on that.

Because my car is a V8, I chose to use a 3.31:1 gear ratio, so I ordered the low-preload diff for the 3.54:1 and down (PN 912A374).  I'm using a 1031 axle from an '86+ car, so it's got the tone ring and speedo drive (I had planned on using this with my Megasquirt for traction control at a later date).  At the same time, Dale Walmsley ordered a high-preload diff for the 3.73:1 and up (PN 912A411), for his 122 which we installed into a 240 1030 rear axle.

When I got my rear end apart, I thought to measure the carriers to see if I needed to buy any different shims.  To my surprise, I needed to add about 0.120" to the ring side of the carrier and subtract that from the other side!!!  Since the factory shims are about .060" each, that meant I'd have to machine material from the carrier to get it to fit.  Obviously this wasn't the right part for the car.

So I borrowed Dale's Trutrac and measured.  It was within .001" of my Volvo diff carrier, so I installed it using the original shims and new bearings, and the gear lash was even better than it was before I pulled the old one out.

Again, I used a 3.73 and up Trutrac (p/n 411) with my 3.31 ring and pinion in my 1031, and all fit perfectly well.  I've also installed the same diff  into a 760 with a 3.73 and it fit just as well.

The taller gears (3.54 and down) have a larger diameter pinion to accomodate more teeth, so the ring gear must be moved further offset from centerline in order to keep the thickness of the ring gear consistent with shorter ratios.  Many manufacturers do this by moving the flange on the diff carrier outboard for the "highway" gears, but it seems that Volvo, in the 1031 at least, used a thinner ring gear instead, and kept the differential carrier the same for all ratios.  I can't speak for the 1030 model diff, since that's closer to a true Dana 30.  They might use thicker ring gears and offset flanges for the 3.54 and down (if they were ever delivered with those ratios).

Another thing that occurred that you should watch for.... the pickup for the speedo may drag on the Trutrac.  My 240 had a light drag, and I didn't bother doing anything about it, but the 760 I did had a HEAVY drag, so I had to clearance the sensor to clear the diff.



UPDATE NOTE:  (JUNE 2007)
-from Mike Perry (mikep at Turbobricks)

Trutrac Installation notes for differentials using Speedo Tone Rings:
For the first tone ring car I installed a Trutrac diff into, I welded a speedo tone ring onto the diff.  It was a big pain. I had to cut the ring apart and weld it to the carrier, then grind down the welds, which were brittle from conduction hardening, so I had to braze the cracks.

Then I did a Trutrac install for Michael Towery.  I cut grooves with a die grinder and cutoff wheel.  It was so easy and worked so well that I only do it that way now.  The grooves need not be wide. The count just has to be the same. I think it's 12 grooves for the speedo.  I'm not sure of the count for ABS.  You can adjust the clearance by sliding the cover up or down, or by using a press in extreme cases.  I have done probably 8 of the Trutracs in total, and the ones for 3.73 gears also work for 3.31 in most cases. The PN 912A411 in the first pic is in a 3.73 geared 1031 axle (my son's car) and the PN 912A588 is in a 3.31 geared 1031 axle.  I also set up a few plate diffs and some locked (welded) for Rob's drift car. Maybe 12 Volvo axles total, not counting repair jobs.

Regarding differential part numbers... the Jeep front diff ("low preload", actually with a different hypoid angle) is a PN 912A314.  I have done plenty of these, but they slip in turns with a big rear sway.

The old number for a Volvo rear with "high preload" is PN 912A411.  I have done two of these.  The new number is PN 912A588... better case material, high preload.  I have done one.  It is the number for high gear ratio numbers, but I think it went in a low number car.

One more bit of info: The diff manufacturers list a split in ratios at 3.51 or something, however I have never found a difference.  I have measured diffs from Jeeps and Volvos with 3.31, 3.55, 3.90, and 4.11 ratios, and ALL were interchangeable. I recently put the new Trutrac PN 912A588 diff in a car with 3.73 gears, and have already put one in a car with 3.31 gears.



UPDATE NOTE APRIL 2008:

Jonas Borgegård of Sweden jonasbakaxel@gmail.com wrote:
I have my own company in Sweden www.bakaxel.se and I sell mostly parts for Volvo.  I sell rear axels and rebuilt BMW/ZF gearboxes to fit in Volvos and other parts.

If you wants ABS you can take the ring from the old differential and "move" it over to the Trutrac (PN912A588).  You need to put it in an machine to take away some steel to be able to get it "on" and move out the pickup for the speedometer 2-3 mm.  I have also made a CAD file and made a water cut metal "plate" that I wrapped around the Trutrac and then welded it together.
   
Here's a discussion thread on installing a Truetrac in a Volvo 1031 rear end:
https://forums.turbobricks.com/showthread.php?t=189043




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