[Ian]

with the no rebuild and no fab rules, you pretty much just have to get a 9 bolt. its stronger than the 7.5 inch rear thats in third gens and its stronger than a 4th gen rear. they came with 2.73's, 3.27's, 3.45's and I think someone makes 3.73's for them, but you'd have to get them put it. However, should you eventually break something in it, be prepared to either pay out the nose or replace the entire rear due to lack of an aftermarket. If by some stroke of pure luck you could find a third or fourth gen with a 12 bolt or a 9 inch, go with that. I'll also mention, that with some fabrication, you could probably get an 8.5 inch ten bolt out of a second gen, 78-81 malibu or a grand national to work but again, you'd have to have some fabrication done to the rear