there are two versions of the 10 bolt for Pontiacs there is the standard 10 bolt and there is the super duty that has the 12 bolt guts look to make sure. The super duty is very tuff and you can put 12 bolt guts into your 10 bolt a lot cheaper then finding and or Buying a 12,Unless that is the look you want. But any 12 bolt from any A-body car from 67-72 will fit.. the 67 is about a a quarter inch shorter both sides of axle and will work and it will give you more room for rubber I have a Olds 12 bolt from a 1967 442 under one of mine... I can run a wider tire.:cheersAny out of a 64-72 A-body will bolt right in, stay away from the Olds 12 bolts they are different from the chevy ones. The Pontiac 10 bolt is a good rear end up to around 450HP. 12 bolts are getting harder to find and they fetch around a grand for good used. Moser can make you one new for a few grand, or for high HP use they will build you a ford 9" to fit your Pontiac. Where you located i have a chevy 12 out of a 69' chevelle with 3:55 gear i may be putting up on craigslist if work slows down. Welded tubes, Strange axles, will need a carrier as its has a mini hub in it now (not good for street use).
No, they aren't - and no, you can't.AND NO DONT STAY AWAY FROM OLDS really the olds 442 rear ends are just as strong and yes they are different Internals and brake the pads are almost imposable to find as with a good gear ratio. But you can remove the Olds pads and inner guts and put in what ever you want. there interchangeable.
And Yes you can.. One of my 68 gtos have a 67 olds 12 bolt and I have had the carrier changed over to a Pontiac safety track with 3:90s that came out of a 1969 Don't tell me it wont and don't it will and dose. My Uncle that owns Six company's that deal's with rear ends and drive lines here in the North west say's other wise .DO YOU do rear ends day in and out? I Don't think SO MATTER OF FACT I KNOW SO. My 67 olds axle has had every thing inside removed and has had a posi from a 1969 pontiac 8.5 put in side And Yes the Bearings have been changed to a heavy duty same as a BOP 12 bolt. Things you can do when you own a Machine shop and family do other thing's automotive. And yes the inside of the housing has been machined for a bigger gear and carrier.No, they aren't - and no, you can't.
Check this page:
Olds FAQ -- Differentials
Note this particular section:
The tern "n-bolt", as pertaining to the rear end of the car, refers to the number of bolts retaining the ring gear to the carrier inside the differential. Fortunately (or unfortunately), this number usually corresponds to the number of bolts holding the differential cover, so you can usually tell whether you have a "10-bolt" or "12-bolt" rear from the number of bolts on the outside of the casing. This is independent of the rear end gear ratio.
The Type O (Oldsmobile) 12-bolt rear ends use a smaller ring gear than the Type C (Chevy) 12-bolt, resulting in lower strength. The good news it that the Type O units retain the axle shafts at their outboard ends, while the Type C units use the infamous c-clips at the imboard end. This is why you see C-Clip Eliminator kits available for the Chevy axles. Also the Chevy rear has a "scalloped" cover where the Olds is smooth.
An Olds 12 bolt rear end is not a "true" 12-bolt. It may have 12 bolts on the outside cover, but it is a 10 bolt gear on the inside. The more common type "C" is very much different than the type "O".
A "true 12-bolt" has come to mean a Chevy c-clip 12-bolt rear. Oldsmobile 12 bolt rear ends differ from Chevys internally. In other words, the guts of a Chevy rear end will not fit in an Olds rear end housing, and vice versa. The phrase, "more like a 10-bolt", is usually talking about the size of the ring gear and/or strength of the carrier. The guts of a 10 bolt would not work or fit in a 12 bolt, and vice versa. There are differences between the 10 bolt and the 12 bolt both internally and externally.
Note also that there are two different ring gear carriers, one for 3-series ratio gears and one for 4-series gears. 3 series and 4 series carriers are for the 12 bolt Chevys. The difference is the dimension from the ring gear mounting flange to the pinion centerline, due to the larger diameter pinion required for the lower numerical gear ratios. A set of 4-series gears can be installed in the 3-series carrier with a spacer and longer bolts (not desireable due to reduced strength), but the reverse is not true.
The ring gear size is the size of the largest gear, parallel to the wheels. A 12 bolt Olds has a 10 bolt carrier that measures 8.3", whereas a 12 bolt Chevy has a 12 bolt carrier that measures 8.8". A 10 bolt Olds out of a 1971 has a 10 bolt that measures 8.5". 1968 and 1969 10 bolts might have an 8.2" ring gear. Starting in 1970, 10 bolts might be 8.5". Newer 10 bolts found under the last RWD Cutlass and Chevy are little 7.5".
Oldsmobile bolted the axles from the inside of the housing, whereas Chevy used c-clips. As for Buick and Pontiac, they used different types of posi actuating items called "cones" and "spools", whereas 12 bolt Chevys and Olds used what are called "clutch packs".
Type "O" Oldsmobile Rear Ends
The biggest weak spots in Olds rears are the wheel bearings and the availability of parts. Positive axle retention is good, but put in the new "updated" style wheel bearings for more strength.
Gears for the Olds 12 bolt rear are hard to find. The "O" was only manufactured for 2-3 years. So there isn't enough call for someone to start casting and machining new cases. While posi cases are not available (as far as I know) rebuild kits are. Unless the case you have is outright cracked or otherwise junk you should be able to rebuild it.