What Chevy 12 Bolt rear do I have?

[GotSomeRust]

I got a Chevy 12 Bolt rear end that I want to put under my 84 Cutlass. Can anyone tell me what it came out of? It measures 58 inches from the tip of one axle tube to the other. The letters/numbers I see on the case are "CONI" (lower left), "J108" (lower right), and it has line 1 "1 2 3 4 5" line 2 "6 7 8 9 0" on it. Thanks

 

[tnts79]

I got a Chevy 12 Bolt rear end that I want to put under my 84 Cutlass. Can anyone tell me what it came out of? It measures 58 inches from the tip of one axle tube to the other. The letters/numbers I see on the case are "CONI" (lower left), "J108" (lower right), and it has line 1 "1 2 3 4 5" line 2 "6 7 8 9 0" on it. Thanks

Well it was built in October of 68, probally used in a 1969 vehicle, there should be another code on the other side of the axle tube. That will give you more info as to axle ratio etc.. It's better to know flange to flange or drum to drum dimensions rather than tip to tip...? Im going to guess and say either a 69 chevelle or a 69 elky

 

[GotSomeRust]

OK, here's the rest of the info on the rear end. It has GM58 on one side and casting number 3959038 NF on the other. It measures 55 1/2 inches from outside of each flange (55 inches from inside). What is it from? Thanks

 

[GotSomeRust]

Got the info. It came from a 69 Chevelle...

 

[GotSomeRust]

Can anyone tell me what I need to get and do to make it fit under my 84 cutlass? Thanks

 

[tnts79]

I am currently working on getting a rear similar to yours in my malibu. You can either buy new rear wheels with 5.5" of backspacing...., or have the rear narrowed. I measured mine and got 55.250, same as what CarCraft got when they did the comparison for G-body rears...? I am having my 12 narrowed 1 9/16" each side, ordering a new set of Moser axles, c clip eliminators, (if your car is faster than 12.99 in the 1/4 it's a must have item)upper adjustable control arms(iceman maliburacing.com), and umi lower control arms. All in all I will have about $1000 in my 12 bolt, it's been just laying around for years, time to do something with it! Good luck with yours, keep us informed, if you have any questions shoot me a pm.