rear diff question

bulldawg1081 · October 23, 2004

i have a 1989 GMC 1/2 ton pickup and the rear axle is going out(its the new style GM 10 bolt) is it possible to put the old style gm 12 bolt axle (?- 1981) in my truck or would it be too much work?

Blue-2001-Z71 · October 23, 2004

i have a 1989 GMC 1/2 ton pickup and the rear axle is going out(its the new style GM 10 bolt) is it possible to put the old style gm 12 bolt axle (?- 1981) in my truck or would it be too much work?

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Not too much work, you'd have to find a whole axle assembly (3rd member, axles, etc) to make the swap work. I'd highly reccomend what you've got in mind, should be a great improvement over the OE 10 bolt. To be on the safe side I'd rebuild whatever you get (new bearings, pick a ring/pinion you like, locker perhaps?). It could get expensive, but I think you'll like th results.

bigjames4xl · October 24, 2004

Unless you're overloaded with horspower a replacement 10 bolt will be fine. With a 12 bolt you'll have yoke issues and possibly driveshaft length issues as well. I'm not sure about the width on truck rears on pre 88 but it's something to think about also.

I just picked up a used 10 bolt from the pick and pull yard for $125 that was is very good condition complete with brakes and drums. I had to change the e-brake cables over from my old rear since the donor truck was a different wheelbase but other than that all went well.

bulldawg1081 · October 26, 2004

I appreciate the responses,im going to see what the differences with the 12 bolt as compared to the 10 bolt, im not overloaded with horsepower by any means but the old 12 bolt has made a very good reputation for its self. Ive shelled out a many a 10 bolt and have never had a problem with the 12 so ill just see what i can find out....thank you guys!

357mag · October 27, 2004

A 12 bolt rear end will give you about 3/16" more tooth contact betwixt r&p. Unless you are sporting 400 HP or more, the 10 bolt, 8 1/2" rear should be fine.

Tim sends