I picked this up yesterday to use in my '66 Skylark. It was reportedly taken our of a '68 Cutlass. Looks like a 10 bolt 8.5". The seller claimed it is a posi 3.08:1 gear set. I've tried to look up these casting numbers but my google skills are lacking apparently. The code stamped on the axle tube doesn't seem to match what I can locate, and I don't see (at this point anyway) any other codes stamped into the housing other than what is shown here. Any help appreciated!
Really appreciate the help guys. I pulled the cover and confirmed posi and the 40 13 on the ring gear indicates 3.08:1. Am I correct in thinking that the large stamped ‘A’ on the housing indicates it’s probably a Buick rear end? How did you guys know? Curious on where I went wrong in my searches.
Mine is just experience of 35 years of parting out 1000's of rears. I do have the buick code in my data base here too. Brian and I just know that rear in our sleep. Jim
Heh - that’s fair. I’m not really well versed so the help is appreciated. Any tips for making sure the 8.5” is ready to be installed? Should be a straight bolt in from what I gather (although 1 inch wider than my stock 8.2). I mean as far as bearing health, ring wear, posi clutch packs, etc.?
If you still have the original 66 8.2 bolt-in axle rear in your car, you can pull the axles and unbolt your backing plates with your brake cylinders/lines still attached, wire them up out of the way, do the same with the 8.5 rear, you can swap the 8.5 rear in, bolt your 8.2 backing plates on to the 8.5 housing, slide the 8.5 axles back in, and you won't even need to bleed your brakes....unless you want to.
Drive shaft will need a a cutr likely unless you do not have the original in it. 8.5 pinion shaft is longer than any other GM A body rear swap.
Hey now - that would be great. Will the 8.2 drums and backing plates fit this rear end even with the bolt in axle (so same thickness of backing plate)?
As Jim(monzaz) said, you will need a shorter driveshaft. If yours is still original, it is a 2 piece driveshaft(one tube inside of another with vulcanized rubber between them. Much like the harmonic balancers, the rubber dries out over the years and the tubes can rotate and that will change the u-joint alignment and cause a vibration or worse. It's best to have a new one piece driveshaft made. Don't even bother with trying to have your original shortened. The 8.5 is a bolt-in axle like your 8.2(if it's the original factory Buick 8.2 rear). No c-clips. Keep the 8.5 axles with the 8.5 rear, and the 8.2 with the 8.2. Pretty sure they don't interchange.
So, update on this. I took a look at the axles and it needs new bearings so I took it to a differential shop for new bearings and a re-seal. They say it's a 8.2" rear end, citing the 10 bolt cover, 10 bolts on the ring gear, and the two inward facing indents on the cover. He says he called around and the other folks he's talked to say it's a 8.2 and not an 8.5. So, any chance it could be? Or should I take it somewhere else? Any advice is appreciated.
The fact that Jim and Brian agree to me means that person doesn't know what they are looking at. I would find someone else.
