This isn't in my Buick, but a Nova I just bought has a 10 bolt with a 2.73 posi rear end. The PO supposedly swapped in these gears and a posi unit at some point. I want to change to 3.73 gears. So, Is there any way to tell what size ring gear it has from the outside? It looks as though the 8.2 can support a 3.73 R&P on the same carrier as the 2.73s and if it has the 8.5 I would need to change carriers. I also noticed in a parts catalogue that they have different spline counts on the axles, one is 28 and one is 30. Is this correct info? Can I do this job myself with the axle in the car?
'68-71 Nova's equipped with 10 bolts came with 8.2 chevy 10 bolts. On the Chevy 8.2 rears, there will be u-bolts & nuts & lockwashers holding the u-joint on, not so on the 8.5's. Further, all '72-75 Novas had 8.5's from the factory. For '76, things got more complicated as the weakest GM X-bodys offered from this year through '79 received 7.5 rears. The 7.5 rears can easily be spotted as the axle tubes are 2.6" in diameter vs the 3" axle tubes used in earlier X-body rears. Even by '79, a few Nova's still used 8.5's. In the late 80's-early 90's our local Pick-N-Pulls & crusher yards always had excop car (350) '79 Nova's & many '78 & 79 305 Nova's... all had the 8.5's, & I usually pulled them all. Had to have cores to build off of. On 8.2 Chevys, the carrier cutoff is 3.08. If one has an 8.2 with 3.08's, the carrier will support 3.36's or aftermarket 3.70's or 4.10's. Personally seldom build the Chevy 8.2's, what with new posi & new gears, one will easily total over what a probuilt posi 8.5 X-body rear will sell for outright, & the 8.5 is much stronger. Last, correct ring & pinion set-up is best left to the pro's & a bench build will always run less than in the car. :3gears: Roger
Thanks for the info Roger. It must be the 8.5 then. It is a '72 with the original rear end and it uses the bolts and straps on the u-joint, not the u-bolts and nuts. That should answer my question on R&P options. I checked the gearing by rotating the wheel and counting revs on the shaft. It was right about 2 3/4, definately not 3 or greater. It also runs just over 2000 rpm at 60. I'll check out my gearing options from there.
