I picked up a rearend from a guy and I'm trying to figure out what it is. What I was told was it came out of a 71-72 Oldsmobile 442. What I know is that it is a posi, 3.91+/- gear ratio and has bolt in axles. Front of passenger side tube has T0 0 081 stamped in it. The front of the carrier housing has the following info cast into it 407286 in one area and the letters CFD in another. I know there are several Buick/Olds guys here and thought someone could help me out. Thanks, Alan
It will be either an 8.5" 10 bolt or an "O" style 12 bolt how many bolts does it have on the diff cover? have a pic of the diff cover? you can check out the differential ID section on JD race's site too for good information http://www.jdrace.com/
http://www.442.com/oldsfaq/ofdif.htm#DIF Differential Identification Appears this is from the '69 model year.
If the bolt in axles are original to the housing it sounds like a 8.2 BOP rear end, regular 8.5s had c clip retention from the factory.
In 71-72 the 8.5's in Skylark/GS, and Cutlass were bolt in axle. The later 8.5's like in the GN's were C Clip.
The rear si a 12 bolt olds TO code which is 3.91 BUT could have more gear if the factory swapped when it was ordered 4.33 4.66 5.00 . Should be Posi also. If it uis a 69 it will only have 28 spline axles. The rear cover should have 12 bolt and be pretty much perfectl round diameter. The ring gear will be 10 bolts held in with 7/16" bolt and 3/4" socket bolts.... They should be Left hand thread bolts in the 1969 1970 era. Yoke will have 2 u bolts and 4 nuts hold the u-joint in place. This rear will be a direct bolt in for 1967-1972 Buick Olds And Pontiac (exception 71 72 Buick and cutlass 8.5 10 bolt era) A-body cars and 1968-1972 Chevy A-body cars with a u-joint conversion joint. Jim JD
Thanks that's good to know, I never heard about factory bolt in axles on a 8.5 before. Do the carriers and gear sets interchange between the c clip rear ends? Back when my 8.2 failed I would have liked to keep it for the bolt in axles but with that one I found the gears and posi were way more expensive than the garden variety 8.5, besides it doubt it would have lasted behind a stage 1 BB anyway, a twelve bolt made a home there instead. Paul.
Yup, All the 8.5 stuff interchanges. I have a rear out of a 71 GS350 in my 70. I stuffed it with upgraded 30 spline Moser axles, and an Eaton 30 spline Posi with 3.73 Yukon Gears. Same parts for C clip or bolt in rears.
I'm going to have this rear freshened up so I can install it in my 1966 Skylark. I know that the rear is about 1" wider but are there any other issues with this swap or will it bolt right in? I posted some pics of the rear here http://rides.webshots.com/album/563632185YhjPFU
