Could my 3.9 diff work on a 2.5 RS or WRX?

Adam West · Post by **Adam West** » Mon Jan 28, 2008 8:00 am

Hey, I have someone interested in using my stock 93 SS (non-LSD) rear differential for their 2.5 RS build?

Question: Could you swap this diff onto a 2.5RS or WRX? I guess there were two different styles of halfshaft and there's a "newer style"...

Anyone know if these will mate and be compatible???

I mean usually it's the other way around - will those cars' parts fit on our cars <grin>

Thanks in advance for the input.

AW

Arctic Assassian · Post by **Arctic Assassian** » Thu Jan 31, 2008 3:52 am

I sold my 3.90 vlsd to a guy with a 2.5rs. It wont match the wrx tranny though.

Adam West · Post by **Adam West** » Thu Jan 31, 2008 9:23 pm

Interesting. So there is a difference between 2.5 RS and WRX shaft/linkage...Can anyone explain this difference to me? Old style, new style?

Thanks!

AW

Arctic Assassian · Post by **Arctic Assassian** » Thu Jan 31, 2008 10:36 pm

The wrx has 1.1:1 transfer gears in the tranny, the rs and legacy have 1:1 transfer gears. The rear diff for a wrx is like 3.54 something.

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Could my 3.9 diff work on a 2.5 RS or WRX?

Could my 3.9 diff work on a 2.5 RS or WRX?