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Should be the same 10 bolt cover 12 bolt gut/ ring gear, pontiac 31 spline rear. All these carriers should interchange from housing to housing. with correct yoke interchanges. Same design was used into the mid seventies with minimal changes ...BUT the rear became c-clip rear and the splines changes ...

No you do not need to as I amn sure this is what it is and it will be 28 spline 45 degree spline. You will need a 3 series posi we have 3.08 gears good used GM for 45.00 we have 3.23 gears good used GM 95.00 3.42 New aftermarket for 139.00 3.73 New aftermarket for 139.00 Rebuild kits New posi units ...

gonna be about 300.00 for that unit.

We should do the flange measurement first before anything to be sure the units are correct. Jim

mmcilroy, VERY familiar with this rear. It is the corperate 10 bolt 8.5...same as all the 70 rears and used all the way up to 1987 grand nationals and it is still used in the trucks to day in a slightly modified carrier bearing and axle spline way. Your diff will be identical to the 1971 1972 Buick ...

12 bolt corp rears were bolt in and c-clip version. early ones really were PONTIAC full size rears from 1965-1970 these were all 31 spline same as the olds 31 spline and were all bolt in axle rears. Then in 1971 -1980ish were used in HD application they were all c-clip and first 71-74 ish were 31 sp...

WOW BBM, Sorry ti took so long to return this post...MY Fault. Ok well not to burst your bubble here BUT about 3.42 might be as high as these rears ever got. I have a set of 2.73 that is about as high as I have seen so far under a car with the FULL SIZE 'O' Type rear. 698 2 series 2.56 ONLY and 700 ...

Ok fixed the carrier breaks and appreciate the Helpful book work for everyone with the full size Pontiac 10 cover 12 bolt ring gear rear with 31 spline bolt in axles. I am a bit confused as to what your asking about the 12 bolt fitting in the 10 bolt? Please elaborate on that? Do you have a 10 bolt ...

If you have an old GM drum install it on backward with about 3 studs just on the end threaded so the drum will slide from the flange to the nuts you just installed...Use the drum as a slide hammer and keep yanking till the shaft pops out. A slide hammer rented from a local advance auto etc will also...

I have a 12 bolt full size Pontiac posi on the shelf but i am sure it is not a very steep carrier probably the highest gear would be 3.08 on it.

Jim

Ok Jeff, 68 Catalina wagon is going to be a tough find for gears and even the posi unit. Here are the ratio available from the factory. NO gears at the moment are available from the after market...BUT they ARE coming. Carrier breaks I am a bit foggy on...Yes even I do not know it all...lol. Here is ...

Yes the posi does need this additive to work correctly. Chatter shock is not super great for the posi unit... It is a inconsistent slip and grip of the cones and or clutches which will in turn send shock through the spider gears and over time will pound the gear face surfaces shortening the life. Ye...

No way is a MONZA weight car going to brake the Moser housing 12 bolt rear with ford ends and 33 spline axles even with just a eaton or true trac. I use a 10 bolt 8.5 with GM axle full spool ladder bar set-up caged car and it does 1.40 60 foot pulls the fronts and runs low eleven high 10.90 so it al...

Hi Paul, Yes we can build the H-body rear. If you using the torque arm it does limit you choices. If you are racing the car mostly and have not much street time at all then a ladder bar set-up is the way to go. If you need it still street able them a Moser 12 bolt center for an f-body and plan tubes...

Gosh...Sorry for the long time frame. Yes the axles for the 8.5 10 bolt are the same for the 1985-87 442 as they are for the Grand National rear. We can get you aftermarket axles. Moser sells them and we have buy in deals from Moser and can get them for a pretty good price too. YOU need 28 spline as...

Yes that is the only thing it could be...BUT... but... ONLY after you remove the defective bearing can you tell if the axle shaft press on surface is good too. IF the bearing has spun on the axle shaft the axle is also doomed. I am crossing my fingers for you that it is ONLY the bearing...WHICH is n...