Even though I have 2 Cutlass' I am more into B-bodies. There is a lot of "mystery" about the different years. The earlier years (65 up to and including 70)had two different rear-end types. 65 & 66 had the "pontiac" type and in 67/68/69/70 had the full-sized Olds 12 bolt(different from the A-bodied Olds 12 bolt.) Nobody makes "anything" for these rear-ends that I know of. Starting in 1971 Olds B-bodies went to the Corporate rear ends. My 71 Delta (455cu.in. 2-barrel) has the corporate 10 bolt 2:73 gears but I have a 1971 Olds 98 (455cu.in. 4-barrel) has the corporate 12 bolt also it is a posi. I have heard the 4-barrel 455's all got the 12 bolt but who knows for sure but it was true in my 98's case. These rear-ends will interchange up to and including the 1976 B-bodies. Ken

 

Have you tried Drive Train Specialists?

http://www.drivetrainspecialists.com/categories/gm/

 

Hello Joe, A few years ago I was trying to find 3:42 or better gears for my 67 Olds 98. I couldn't find any after-market or a factory gear for the 1967 housing. I ended up putting a 3:08 posi from a 1965 Olds 98. I do have one "spare" from a 66 Delta, these are the "pontiac type" that were standard on the 65/66 Olds B-body. In 1967 Olds went to a different, a little bigger ringed geared housing 12 bolt. Car weighs 4680# with switch-pitch on switching to "lock-up" at the 60' mark the best I can get is a 2.0 sixty foot time. If I had better gears I could knock it down a lot. Car runs 14:18@100mph. Ken 3-14-2007-42.jpg

 

Try giving these guys a call. They have been doing rear ends around Chicago since the 70's. They scored me a new ring, pinion, shims and bearings for my 85 Delta for 75 bucks, so naturally I like their shop haha. There is a boneyard a block away from there too with all kinds of crap.
Suburban Driveline
747 W North Ave
Villa Park, IL , 60181-1322
Phone: 630-941-7101