I picked up a 92 Legacy FWD Auto with a bad diff. The tranny seems to not slip and shifts good. Could I just swap the diff with one off of another auto tranny?

Should be able to, yes. But since the tranny has to come out and obviously has had a lack of maintenance..... it would be most cost effective for time/materials to just swap in a good used transmission. Unless you happen to have a bad auto with a good diff. That's about the only time it makes any sense.

 

GD

it would be most cost effective for time/materials to just swap in a good used transmission. Unless you happen to have a bad auto with a good diff. That's about the only time it makes any sense.

 

GD

 

I agree.

 

I have done this twice now. Used Ring and pinion from a poorly shifting burned up trans to fix good shifting trans with bad front diff. (once was actually mostly about fixing a speedo drive gear)

 

You need to get the gaskets for the front case and tail section matings. And Most importantly a new "Seal Tube" for inside the diff case. Splurge for side seals and cup o-rings while you're at it.