Hey Dana experts! Looking for help identifying a Dana differential with 2.76 gears

[jayvee]

I am hoping I can get some help on what I am told may be a Dana 44 differential which is currently installed in a 56 Ford F100 and I have no history on the build. My attempts to identify on line have been unsuccessful, but I did learn that Mopar did use Dana's with 2.76 ratios, so maybe the donor was a Mopar somewhere along the line? The cover has 9 bolts, not 10. The numbers 3723675 are cast at the upper rear on the driver side and 23258 or maybe it's 28258 appear at the upper passenger side. Two metal tags are at the bottom, one read 2.76 and next to that is a tag with 2016. Thanks VERY much for any help you can offer. I would like to add posi-traction to this differential so any advice on that would be a definite bonus. Thanks again.

 

[Beekeeper]

kinda looks like a Borg Warner 9 bolt rear but not sure

 

[jayvee]

Funny you should say that. I just now, I happened to stumble upon the site www.9bolt.com. Thanks for the reply!

 

[1 Wild R/T]

lower right is dana 44

 

[jayvee]

Maybe the design changed from back whenever this differential was manufactured? It's close to the picture you sent, but not exact and the 9 bolt instead of 10 bolt is confusing me. The Chrysler 7.25" at the top of the chart is actually closer and apparently was made with either 9 or 10 bolts. I'm hoping I don't have some weird, off the wall rear end. Maybe more replies will clear it up! Thanks.

 

[Photon440]

If it is the Borg Warner rear, it's also known as the M78. They were common in 3rd gen Iroc Camaros and Trans Ams, were a lot stronger than the old GM 10 bolt.

This is a 3rd gen. cover (inside view):

 

[1 Wild R/T]

From FABO

7 ¼
Junk.read no more. Introduced in 1960; it was a low performance axle for /6 and small V8 cars. Before you swap this unit out put some slicks on your car..rev up the engine good and launch real hard a few dozen times. Or street race your car for a night or two, or objective here is to blow it up.
The rear end will eventually go KABOOM. Lots of fun for all….bring a tow strap so you can get home. Casting numbers # 2070051, 3507881, 3723675
Info: 1 3/8" Pinion stem, 9 bolt cover, 55.6" width (flange to flange) / 53.2" housing flange to flange / 43.02" spring seat centre to centre.
SPECIAL NOTE: The 7 ¼ housing axle tubes are smaller in diameter than other units so the u-bolts and spring plates are useless if converting to a larger axle (i.e. 7 1/4 to 8 1/4, 8 3/4 or bigger).

 

[Cranky]

Do you have something like a pair of straight calipers that you could measure the OD of the ring gear? Get close and then measure the caliper tips with a tape or ruler.....if it's close to 7 1/4" then that's what it probably is but looks to me 1 Wild R/T already called it. Measure the diameter of the axle tubes and see if they are less than 3" in diameter.

 

[jayvee]

From FABO

7 ¼
Junk.read no more. Introduced in 1960; it was a low performance axle for /6 and small V8 cars. Before you swap this unit out put some slicks on your car..rev up the engine good and launch real hard a few dozen times. Or street race your car for a night or two, or objective here is to blow it up.
The rear end will eventually go KABOOM. Lots of fun for all….bring a tow strap so you can get home. Casting numbers # 2070051, 3507881, 3723675
Info: 1 3/8" Pinion stem, 9 bolt cover, 55.6" width (flange to flange) / 53.2" housing flange to flange / 43.02" spring seat centre to centre.
SPECIAL NOTE: The 7 ¼ housing axle tubes are smaller in diameter than other units so the u-bolts and spring plates are useless if converting to a larger axle (i.e. 7 1/4 to 8 1/4, 8 3/4 or bigger).View attachment 1354625

Hey thanks for the "good news" 1 Wild R/T! Good to meet a guy who actually says what he thinks!! Looks like instead of trying to alter this one, I should be looking at a swap into a Ford 9 inch. I appreciate your help on this, now I know what I have.

 

[1 Wild R/T]

I was gonna suggest a different axle but re-read the first post, 56 F100, yeah, 9 inch.. Cool truck..

 

[Runcharger]

My brother was a dealership mechanic in the "golden years". He said those things wouldn't stand up behind a slant sicks.
Ironically I believe a 56 Ford P.U. came with a Dana 44 from the factory so someone downgraded it when they "improved it" a common practice these days it seems.
Lots of good choices now though, I'd go to a modern wrecking yard and find something out of an SUV or pickup that has the width and ratio you want along with a set of factory engineered disc brakes.

 

[jayvee]

My brother was a dealership mechanic in the "golden years". He said those things wouldn't stand up behind a slant sicks.
Ironically I believe a 56 Ford P.U. came with a Dana 44 from the factory so someone downgraded it when they "improved it" a common practice these days it seems.
Lots of good choices now though, I'd go to a modern wrecking yard and find something out of an SUV or pickup that has the width and ratio you want along with a set of factory engineered disc brakes.

Probably discarded the Dana 44 in order to get away from the 3.92 gears or whatever was in it in order to get a more highway speed friendly ratio. Who knows???

 

[Cranky]

The 7 1/4 that came in my 66 /6 Belvedere had 2.94's and well, it got abused as much as a /6 could give and it stayed together but it was eventually replaced with an 8 3/4 with 4.10 gears.....and in the swap I got rid of the impossible to find 10x1.5 brakes too.

 

[jayvee]

You guys got a recommendation on gear oil I should be using in this 7.25?

 

[Cranky]

You guys got a recommendation on gear oil I should be using in this 7.25?

Doesn't really matter with the the 7.25 because anything over 200 to the wheels will destroy it slowly.....imo.

 

[jayvee]

Doesn't really matter with the the 7.25 because anything over 200 to the wheels will destroy it slowly.....imo.

“Anything over 200 to the wheels”???

 

[Cranky]

“Anything over 200 to the wheels”???

Probably more like 100.....

 

[33 IMP]

“Anything over 200 to the wheels”???

200 wheel horsepower.
Frankly, I would recommend an explorer 8.8. Can find a range of ratios, limited slips, and come with disc brakes and a width that would work in your pickup.
(and probably a quarter of the money of an equivalent 9", and probably 90% as strong).

 

[dvw]

I agree with the Ford 8.8. Cheap, disc brake. I'm pretty sure the common ratios are 3.55, 3.73, 4.10
Doug

 

[dana44]

Looks like a 7 1/4, you have plenty of options to swap, ford 9'', ford 8.8 the 8.8's seemed to get a little expensive thanks to the jeep guys. a quick find would be Chrysler 8 1/4 found in many of the nearly 3 million xj's made. You may come across a 44 in an xj but those are hard to come buy because of guys like me.