I'm trying to go back to stock on our '97 impreza wagon (originally 3.900 and I had converted it to 4.111). Re-installed a 3.900 transmission along with a 3.900 rear diff from a '95 Brighton (tranny type 752VT4AA). For some reason, the inner joints don't want to pop into the diff. I've always felt there's no difference and I must be doing something wrong. Any thoughts?

I doubt this is helpful, but recently someone else discovered there were 2 different sizes of circlip.

 

Dunno exactly what this means - maybe someone else will know.

The solution has been discovered. It wasn't the axle, it was the rear diff. Altho it was a 3.900, it was JDM version and it takes an axle with 22 splines on the inside; USDM versions have grooves for 25 splines on the inside. As far as I know all '93 to 2001 Impreza use the same axles and 25 inner spline diffs.