I was originally thinking about getting a 4thgen rear end, however after doing quite a few searches and getting some info, really, there's no performance gain associated with a 4thgen rear.

I already have rear disc brakes, I already have posi and I already have a decent gear ration (3.23). BUT - The rear is whining REALLY badly. Its been ok to drive on for the past 2000 miles but I don't want to push it.

Anyhoo - I really like the idea of buying a NEWER rear, but having to go through the trouble of spacers or buying different wheels, when I love the IROC wheels, just doesn't make the 4thgen rear sound any better to me than my 3RDGEN one.

So - Unless I find a 4thgen rear CLOSE or CHEAP, I am going to be hunting for a 3rdgen rear end, with disc, posi and 3.23 or 3.73 or something similar.

Question is, I hear everyone talking how the 89+ rears are so much better... Why is that? Bigger brakes and better calipers? Are they harder to find?

Being that Idaho sucks, there are no yards within 100 miles that have any useable parts... Is there anywhere online that sells them cheap?

 

The PBR brakes are the biggest benefit to the 89+ rears. They also come with the 28-spline axles which are stronger than the older 26-spline (not sure what year they changed that though.)

Try the classifieds section of this site, Hawk's 3rd Gen (link at the top of the page) and 3rd Gen Resource (also link at the top.) Those will be your best bets for a rear.

 

You won't find a 3.73 in 89-up axles (with the PBR rear discs)... they stopped 3.73's in 1985.

It might be more cost-effective to fix your current axle. It's certainly less hassle. (I swapped in an '84 3.73/posi/disc axle and man, the brake system was hell. Granted, I was swapping from rear drums to discs, though...)