Rear axles for Autos and Manuals are different!

[smokeythewhitewagon]

Just wanted to post a new topic to let everyone in on a little known fact.

The rear axles and rear differential casings are very different from automatics and manuals. (at least on BD/BG's)

This was a frustrating lesson for me, and hope this posting will simplify the lives of my fellow RU'ers.

Junk yards might have them inventoried as the same, ( :smt018 ) but make sure they have pulled it the matching transmission type.
Ironically, the fronts seem to be interchangeable.

[greenspeed]

Pics to prove this?

[mike-tracy]

So I did a little digging. Opposed forces shows that there are two types for the 2nd gen's, but not between manual or auto. It's early vs late style. In the pics take note of the bearing caps. That's where the main differences lie (and as to which axle type it uses).

Early style:
https://sl-i.net/FORUM/images/imported/2012/05/366494919501png-1.jpg


Late style:
https://sl-i.net/FORUM/images/imported/2012/05/366494919502png-1.jpg

The main "carrier" is the same part number between the two, but the ring & pinion varies (for different FD ratios) as well as the bearings, shim's, and a couple other minor pieces.

[smokeythewhitewagon]

Mike- You're awesome! :smt023

I went to a Subaru Dealership, and the tech there looked up the part numbers for auto and manual axles, and they had different part numbers, so we figured that was why there were different axles and casings.

What's really weird is that my 95 has the Late style whereas my 98 has the early. Seems backwards.

Thanks for the pic, THAT'S exactly what I was battling. The axle caps are different for those two casing types.

[greenspeed]

I ran a 02 auto wrx rear diff in my 98 bd no problems...thought it was weird to see an auto/manual difference. It's subaru after all if they want a change they use stub shafts lol

[smokeythewhitewagon]

Junk yards might have them inventoried as the same, ( :smt018 ) but make sure they have pulled it the matching transmission type.

So I guess just make sure your differential casing type matches. :smt023

[country side drifter]

yes i dont think subaru has much different diff casing. i have put a 2000 legacy auto outback lsd in my 98 5spd no problem. just the axle where not a match but i was because the outback had rear disc and my brighton has drum. but i took the axle and put the in the lsd outback diff.

[Grafton]

I ran a 02 auto wrx rear diff in my 98 bd no problems...thought it was weird to see an auto/manual difference. It's subaru after all if they want a change they use stub shafts lol
I have an 05 WRX rear diff in my car, and on top of that it's from an automatic lol

[greenspeed]

I ran a 02 auto wrx rear diff in my 98 bd no problems...thought it was weird to see an auto/manual difference. It's subaru after all if they want a change they use stub shafts lol
I have an 05 WRX rear diff in my car, and on top of that it's from an automatic lol

Mine was an auto diff as well, the manuals have a 3.9 FD iirc the auto's were all the 99+ 2.5rs diff so 4.11