I am considering upgrading the new Skylark with an Oldsmobile type "O" rear end with 12 bolt cover/10 bolt 8.5" ring gear with bolt in axles. I beleive this has the '67-'69 early axle bearings. Is it suitable rear for a mildy built 455 w/ TH400 or am I asking for trouble? The housing casting # 394139. Currently 2.78 gears w/posi which is ok for the driving this car will have for the near future.
Nothing wrong with the rear, just more expensive to build, http://www.v8buick.com/showthread.p...tta-u-think&highlight=oldsmobile+12+bolt+rear http://www.jdrace.com/diff_id/12bABodyOlds.htm If it were me, I'd look around for a 71-72 8.5 10 bolt.
I had a good one and scrapped it. Not because they arent good, but because parts are real tough. There are many better options out there. Stay away from the O type. Brandon
If it is in good shape and not many bucks, go for it. I bought a posi carrier from Monzaz for my existing 2.78 gears and loaded it up. It has the bolt in axle so you are ahead of the c-clip guys to start with. Bearings are available so that isn't a big issue. I'm not sure what the costs are for new clutch pack inside so that may vary. Now if you need new gears, yeah, you are pretty well screwed or so I hear, but if the existing gears are ok, go for it.
Ye, just a short term piece that is in working order and realtively cheap. I usuallly don't fuss with BOP rear and build chev cases and afertmarket guts.
Nothing wrong with most BOP rears. Some are just worse than others as far as parts. The O type being 1 of them. I would take a BOP 8.2 over a Chevy 8.2 any day. Same with the 8.5. You get factory bolt in axles on either. Brandon
We just have to wait out Motive gear and axles which bought out Richmond. We need them to start reproducing the 3.42 3.90 4.10 gears again. THIS is the only thing holding up the works. We have 2 series posi 3 series posi and i can even help get the 4 series unit in the olds. Bearings are always available. If you guys had to build the import rears you would appreciate the cost of building your Muscle car rears. LOL. JIm 3000.00 in parts ALONE no labor for gears posi and bearing that was just for the IRS unit no axle bearings... All parts had to come from Nippon JAPAN!
