Im near ready to modify/swap out the rear end in my 1969 Cutlass, car was born with a peg leg and gears that dont suit my driving style (2.73) or something like that, dont recall exactly anymore. Anyhow im wanting a posi and something in the 3.55 to 3.73 ratio range. Seems i recall modifying the existing rear end was cost prohibitive? Any options for a direct bolt in from another Olds or? Im running a BB and M21 close ratio drivetrain. Thanks for the help in advance.

 

Before we give advice you need to clarify which rear end you have now. It will be a type o 12 bolt, a type c 12 bolt or one of a variety of 10 bolts. Which do you have?

 

I honestly dont know Dave, what is the procedure for correct identification? Thanks

 

www.jdrace.com has a I D Differential or you can snap a few shots of the rear cover that will help us ID the rear. Jim
J D

 

Thanks Guys, will check it this afternoon.

 

Visual inspection showed no id tag, diff cover has 12 bolts. The car was born in the US. Any help?

 

It should be the 12-bolt O-axle. Gears for these are about non-existent right now. I would build a 71-72 8.5" 10-bolt,or a 12-bolt Chevy. If you can't find anything out your way,I have both styles that I can build to suit.