I have a 9 bolt on my '89 GTA 305 manual. And I'm wondering which rears can be put on my car?? I'm thinking of replacing the old one because I believe it might be the cause of a shake problem (I have another thread on that).

My car is stock except for a deleted cat. So which rears from other cars will fit but still be as good or perhaps even better suited for my car performance wise than my original 9 bolt?

 

from a strength standpoint, 9 bolts are the strongest stock rear ends from thirdgens. any 10 bolt from a stock thirdgen would also fit, perhaps a 3.73 geared 10 bolt posi would be a nice swap. Unfortunately a stronger rear is also around $2000+ in the form of an aftermarket moser, strange, etc 12 bolt or 9" style rear end.

 

Fourthgen rears are also a bolt-in option, though there may be some difficulties with the e-brake cables. The fourthgens are also, IIRC, a couple of inches wider per side.

JamesC

 

Any third gen 10 bolt will be a direct swap. They all use the same external dimensions for the suspension. The fourth gen diffs will also bolt in but as mentioned above, they're about 2" wider per side so your third gen wheels will stick out.

If your 9 bolt has the PBR calipers, they won't swap onto a 10 bolt without some sort of mounting bracket fabrication. The early third gens have standard double flare brake lines. All the newer one use metric bubble flare so there's a few more things to think about if looking for a junkyard replacement.

 

They'll swap right on to a disc flange 10 bolt if the backing plates are changed.

 

How is the 10 bolt in comparison to the 9 bolt?

 

As stated above, the 9 is somewhat stronger; it is, however, more difficult to find parts for.

JamesC

 

But if it's the strongest I find it hard to believe that IT is the cause of my problem. It's almost a stock car even. So it must be something else that is worn.

 

The best and strongest wear out, both cars and men .

JamesC

 

The newest 9 bolt is now 17 years old. They don't last forever.