Hi All, Looking at getting posi into the skylark, and just replacing the entire rear end outright. Which do you guys believe would be a better fit? (or fit at all?) 12 bolt posi 3.08 out of a 72 cutlass or 10 bolt posi 3.08 out of a 72 chevelle Thanks for any info/opinions!
Some Oldsmobiles came with a rear that had a 12 bolt cover but 10 bolt ring gear. The 72 Chevelle rear might be a 8.2. Both rears will fit I would think. Parts availability would be better for the Chevy rear. Ask Monzaz to be sure.
Thanks Larry, the person thinks the chevy 10bolt might be an 8.2 as well, but not sure, I haven't gone to check it out yet. If it's an 8.2 would I still need to shorten the driveshaft? Would I need to if it's an 8.5? Not sure, thanks for the help.
Monzaz would know for sure, but I believe the Chevy uses a smaller u-joint, so you may need to use the same Hybrid u-joint as if you were swapping in a 12 bolt. Not sure on the 8.2 drive shaft shortening, but definitely about 1/2-3/4" for the 8.5. Check on Jim's site for Differential ID, www.jdrace.com
THE fitment of the rear will all depend on the differential you have in the car at this time. IF you have a 10 bolt 8.5 in the car right now... You will need to make the drive shaft LONGER not SHORTER. PLUS you will need to change the u0joint on both 10 bolt 8.2 and 12 bolt chevy...IF it is a 12 bolt olds you will not need to change the u-joint BUt you will still need to lengthen the drive shaft or fine a longer one. YOU should KEEP the 109 bolt 8.5 and buy the posi and gears for it as this rear is worth the money to rebuild. IT is strong and parts are very plentiful in the aftermarket with great choices in Posi and gear ratios. Hope you make a good decision. Jim :TU: :Comp:
thanks Jim. since I have the 70 skylark custom, it actually has the BOP 10 bolt 8.2 in it... without posi. and the only option there for me was to get those $500 carriers and gears you have, which was a good option but I decided to get this other 10 bolt rear that is in great condition (I may get a higher set of gears from you for it). Unfortunately I think it's a chevy 8.2, not 8.5. But at least there are parts for it. I was confused because I thought it could be an 8.5, but it doesn't have the "ears" on the bottom, though it has the regular cover, not that "V" cover usually on the 8.2. So I'm assuming I have the chevy 10 bolt 8.2 right now, which is good with my, posi 3.08 so I can still do highway and I got a full set of brakes with it. So do I need to shorten the driveshaft to go from my BOP 8.2 to the Chevy 8.2? Also where can I get the right hybrid u-joint, I've seen certain ones at summit, but people say they need to be machined? Thanks for the help guys! The car is going to love finally having posi, even if I do destroy it when I put a 455 in. But for now with the 350, it'll be fine.
1971-1972 Skylark rear is 10 bolt, 8.5", no C-clips and big u-joints. Best of everything, very strong too. I would swap those 2 rears for one skylark rear in a heartbeat.
so would I Gary, but 1) I can't find one within 300 miles, 2) It would cost $1000+ as opposed to this $350 and 3) I don't have posi now so I just want something in there, and at least there are parts and gears for the chevy 8.2
i have a 273 chevy 12 bolt posi thats a little pitted i will be willing to let go if you are intrested .
I know where there is an 8.5 posi with 60 miles of you. And it is in a Buick Skylark. Posi tag still on it. Not sure of ratio. Never say never. Not sure what they want on price. It may be a little pitted but correct for car.
