I have two Oldsmobile rear ends one off a 1970 cutlass that I’m rebuilding it has a 12 bolt cover so I’m assuming that it is a 10 bolt O type and One of a 70-72 cutlass not sure have no title I was told a 70 which I think is true But it has a 10 bolt cover trying to figure out which one to rebuild I’m wanting to put some 342’s or 373’s and make it Posi thanks for taking your time to read any info would help I am no mechanic but I am rebuilding my grandfathers car and could use some direction

 

Rear ends
I have two Oldsmobile rear ends one off a 1970 cutlass that I’m rebuilding it has a 12 bolt cover so I’m assuming that it is a 10 bolt O type and One of a 70-72 cutlass not sure have no title I was told a 70 which I think is true But it has a 10 bolt cover trying to figure out which one to rebuild I’m wanting to put some 342’s or 373’s and make it Posi thanks for taking your time to read any info would help I am no mechanic but I am rebuilding my grandfathers car and could use some direction

 

Ancient thread. The 10-bolt corporate axle (used '71+) will be much easier to find parts to rebuild. Type-O parts ('67-'70) are available too, but from far fewer sources. If you want to keep that '70 all original, rebuild the Type-O (10-bolt ring gear / 12-bolt cover), but make sure you get the correct axle bearings / seals as they were different in '70 vs. the earlier versions.

 

Thanks for the info. Out of these two rear ends, do u know which one is stronger, and maybe a list of parts needed to rebuild these correctly. Also I have noticed on the car I’m not rebuilding I took a pic of the vin so I can find out for sure what year it is I was told 70 and it definitely has a 70 bumper, but u said these 10 bolt rear ends are 71+, also the car with the 10 bolt cover it has coil over suspension in the back is that beneficial. I don’t know much about this other car but I will find out very soon I guess thanks once again

 

I believe that 1969 was the last year Olds cars were built in Canada. After that year, the Oshawa plant only built Chevys.
Derek

 

The Type O has a 12 bolt cover with a 10 bolt, 8.5" ring gear. It was used from May 1966 through the end of the 1970 model year on A-body Oldsmobiles built in the US. The 10 bolt cover housing, if it has bolt-in axle shafts, is likely from a 1971-72 A-body. If so, the center section is the same as the "corporate" 8.5 inch 10 bolt axle.

 

Rather that dredge up a decade old thread to post duplicate questions, I've merged your posts into your existing thread. It is neither necessary nor in your best interest to spam multiple sections of the forum with the same question. You'll get a better answer sooner if all responses are kept in the same thread, so incorrect info can be identified and corrected.