I bought a 3:42 posi/disc rear end housing as a unit for my sons '91 RS 5 speed and had it installed by a friend of mine. I was told when I purchased the rear end came that it was from a 4th gen car and it was 2 inches wider than the 3rd gen but would fit fine. It did fit up and worked fine until recently when it developed a whine. It turns out the pinion bearing were going south. While we had it opened up we noticed the spider gears were pitted. So I began searching for another rear end or carrier.

I found and bought a 3:42 Torsen (I guess, no clutch packs are visible) 4 channel rear end housing that supposedly came from a '02 TA with less than 40k miles on it. I had planned to just swap the carrier but the problem is this new carrier is a 28 spline and my old unit is a 26 spline, and the new one is 4" wider than the old one so the axles won't work.

Did the 4th gen. rears change width at some point such as when they went from LT to LS?

He also has a '97 SS but it's not here for me to measure the widths.

Bottom line is I still need a 26 spline posi carrier and need to get rid of a 28 spline complete rear end.

 

LTs and LS cars rears are the same width. Your sons car had drum brakes originally so that would probably be the reason a disc brake rear is slightly wider.

 

all 4th gen cars had 28 spline axles. your previous rearend probably came out of a 3rd gen. the only change in width was from 3rd to 4th gen.

 

^^^^I agree...