455cutlass1969

i have a 1969 cutlass with 10 bolt open rear and 3.08 gears. bought a 10 bolt posi rear center section, 2.56 gears, out of '72 olds cutlass. i want to swap in the posi and retain the 3.08 gears any trouble making this swap?

Eddie Hansen

I am not sure but I think the rears are different, I believe they changed over after 69 or 70, so the carriers will be different from 69 to 72 , I also do not think you can use a 2 series carrier for a 3 series gear, I am sure Brian Trick or Monzaz will chime in they are the experts, just thinking out loud...

Eddie Hansen

http://www.442.com/oldsfaq/ofdif.htm


hope it helps bud...

pcard

I do not think you can make this swap. The 3.08 definitely will not sit in a 2 series carrier.

droldsmorland

I’m pretty sure the 70-72 corporates pumpkin will not inter-change with the late 67-69 O types. Put them beside each other and you'll see. You need to find an O type posi carrier. Auburn or others may offer a limited slip clutch pack for the original 308 O carrier?
I just did a 256 O posi carrier fitted to a 308 O ring gear. All I needed for the conversion to work was the spacer and bolts. Of course I replaced all bearings seals crush sleeve etc...Setting the lash and pinion depth is a PITA.

Eddie Hansen

you are sooooooooo right LOL.....

https://classicoldsmobile.com/forums...nvertible.html

pcard

I did not know you could put the 3.08 in a 2 series posi. Can you put a 2.56 in a 3 series?

Jim (MONZAZ) recently had some Auburn carriers machined for The "O" - I got one and put my 3.08 on it - fitted nicely.

2blu442

I agree with the above post. The Type O rear end used from 1967-70 will not accept the corporate unit used in 1971-72. Check with Jim (monzaz) or Brian (507OLDS) for the correct parts if you want to keep the 1969 rear end. The other option would be to acquire a 1971-72 housing and swap the newer rear end under your car. If your not going for a numbers matching car this would give you more options for gears and parts in the future. Lots of aftermarket stuff and even finding parts at your local parts store for the 71-72 rear end. The Type O was Oldsmobile only and its much harder to find parts for these.
John

455cutlass1969

i have the whole 1972 rear end. i will have to swap over the brakes, etc from the one in the car now. it is only the housing, center and axles on the '72 unit. i would want to get another ring and pinion cause i am thinking the 2.56 gears make suck? the motor in my car is a stock 320hp 4brrl with hooker headers.

monzaz

You are good with the 10 bolt 72 8.5 in the olds. Rear will be alot easier to find good used parts for.

Both rears WILL do the job-

So what you need is a ring gear spacer on the 2 series carrier and a set of 3.08 gears. IF you have the money a bearing kit is a great idea as the age of the rear and unknow quantity.

You want a quote on any of this stuff PM me

Jim
JD

455cutlass1969

do you know if i will have any trouble linking my existing driveshaft up the to the rear from '72?

monzaz

You might but it is best to install the rear first then try your old drive shaft and see if it fits. It normally would need a shortening of about 3/4 inch...BUT you may not have an original driveshaft in the car...?? Always try the parts before modifying. Jim

507OLDS

You can reuse your existing brakes,and you can do it without opening the lines.Put the car up on stands,and let the rear hang.Remove the axle shafts.Now you can hang or suspend the backing plates & brake lines,while removing the old rear.once you get the new rear in,install the backing plates on,and install the axle shafts.As long as you didn;t open any lines,you won't need to bleed anything.
What 10-bolt do you have under your car now? 8.2" 8.5"? Do you have a 10-bolt cover,or 12-bolt cover.