That is a 10 bolt 8.5. You are good. Jim Bolt in axles 1 1/4" nut will be on the pinion that is also a Mechanics 3R u-joint. It is a Oldsmobile casting of the 8.5 71 72. Same guts as the Buick casting which is what Brian is showing in the pictures. IF you want to be absolute...WHICH I ALREADY AM.... Put your hand on the top of the casting between the two upper control arms...If the brake line is bolted into the casting and not a bracket from the rear cover IT IS A 8.5 GM rear. YOU ARE ALL GOOD. You have a 8.5 Corp rear Jim J D Race
???? What the heck does mean ??? In American English please... LOL I know your giving a size comparison ...just messing with you...
This info is miss leading to the pictures you have provided. SO you took off the drums and your axles do not have ANY 1 2 3 4 access holes to get to the retaining plates for your BOLT IN AXLES? YOU really need to get pictures of the back side of the drum backing plateas where the housing tube meets the backing plate under the car. They should be round head slug with 1/4 cut off with the threaded end inside the drum shoe and hardware with the NUT inside the drum shoe and hardware area holding the backing retaining plate on inside the drum shoe and hard ware area.
AXLES can have 1 Hole to 4 Holes... usually they are 3 or 4 hole in the 8.5 rears. I do not have a 4 hole picture example at this time but they are very common. oh guess I did find a 4 hole example.
That is good enough. YOU have bolt in axles and I am sure if they are original axles YOU DO have the Holes in the axles for your access to the retaining plate. Jim As said before YOU ARE ALL GOOD...10 bolt 8.5 GM rear 1971 1972 ...Your is just a Oldsmobile 8.5 which they did share these rears all depends on your built plant. I call it the stealth 8.5... they get over looked at most yards for the 8.2 chevy 10 bolts...lol.
I gotta take the drum off and see again, I swear they don't have holes. Thanks for the info, it's much appreciated!
If they are GM they have the holes. That is a BOLT IN AXLE rear absolutely and it is a 8.5 absolutely. Jim
Okay Jim I appreciate it. When I'm ready to buy a posi unit After the holidays, I'll check with you first. Thanks again.
You have an 8.5”. I tried to post more pictures,but for some reason,I can’t. The one under your car is what came under 71-72 Cutlass/442’s built in Lansing Michigan.
Well someone put an Olds 350 engine in the car so maybe they swapped the rear too. Thanks guys, you're a wealth of knowledge!
Highly doubt it was transplanted... It looks pretty stock under there. Like I said it was a shared rear Buick rears were under Oldsmobile cutlasses and vise versa... Your fine all the guts are the same as the Buick rear. BE thankful you have the 8.5 rear that helps in the purchasing of gears posi bearings etc. Less money for the same parts as the 8.2 or any other rear.