I have a question for you all, I want to eventually put a posi with 3.42 gears in and I am wondering what is the best way of doing this. I found the numbers for the rear end but am unsure what I have so if any of you guys could tell me that would be great. on the tube I have numbers R2 B131 2, and on the pumpkin I have 1235197.

 

R2 means 2.56:1 gear ratio.

Since you are wanting to install a posi and 3.42 gears, you can either get a new carrier/gears and have them installed in your axle or you can buy a complete axle with posi/gears. I think it is easier to buy a complete rear with the gear ratio you want as opposed to buying a carrier, gears, installation kit, and paying someone to put it together (it's not a job many people can do themselves). Just my opinion.

 

I don't know enough about the codes to say if that's the original rear end. But if it is, that would use the corporate 8.5 internals. So you can find all kinds of mid 1970's GM cars into the late 1980's with the same internals. An example, a couple years ago I purchased the rear end from a 1974 El Camino that had a 3.42 posi setup. Since there's not as much demand for the 73-77 cars I got the rear end for much less than a 64-72 vintage. Yes I'll have to pay someone to install the carrier and gears into my 71-72 housing, but I'd like to install new bearings and wear parts while I'm at it. Then I'll know the rear end is good to go. So that's the direction I decided to go in. How much money you have to spend is also a consideration. There's lots of threads on this topic, so if you have time you might read through some of them and see what others have done.


John

 

2:56 non-posi,Buick plant,131st day,2nd shift.

The cars that were not built in Lansing,got this casting rear.If the the drums are original,you will find the Buick trishield on the outer face.
Everything sounds correct and original for your car.
You can install a posi and any gear ratio you want in there.
Check with some local shops,and see what they charge for the install.

 

thank you guys I appreciate the help. this is going to make ordering the parts a lot easier and it is nice to know what i have to start with. you guys rock.