72 C10 rear disc conversion and axle swap

[72HawaiiBlue]

Hey guys

First post here. I have a 72 C10 and I've been wanting to swap out my open differential, 3.07 geared rear axle for a posi unit, and bump the gears up. What are your guy's opinion on 3.73 vs 4.10 I have a 700r4 swapped in already. I have a guy that can get me killer deals from junkyards so I was wondering if there are any later model vehicles that I could get the whole 12 bolt out of and take the ring, pinion and carrier out of to get the posi and higher gears, but maybe also find an axle that may have rear disc brakes as well that would swap onto my original 12 bolt with drums. Any information you guys have would be greatly appreciated.

[Bigdav160]

Since the 12 bolt truck axle was last used in 1982, I don't think you'll find modern OE parts that fit. Aftermarket (new) , yes.

Do a search on this forum for rear disc. Somebody might have done it. Not worth it for me but I grew up driving cars/trucks with 4 wheel drums.

[Twisted78SS]

you have several options for an axle swap..

Pretty much any 12 bolt truck axle internals will work, and there are a wide variety of traction or "posi" options both factory and aftermarket to choose from.

** Car 12 bolts are not interchangeable with truck axles..**

As for gearing, maybe just a bit more info would help..

engine size
tire size
Typical RPM range you want to be at for highway driving

I see both 3.73 and 4.10 with an overdrive, it's really a preference on what you are trying to achieve.. economy or performance or the best of both..


While straight forward to do, rebuilding an axle does take some know how and a few tools (dial indicator for one) to do it right and not have issues..

Once you decide on your proffered gear ratio, i would look for an entire setup.

Keep in mind too, that part way through the 70 model year the axle width changed on the 2wd models taking it our 3/4 of an inch on each side..

[snipescastle2]

Captainfab has several kits available, I bought his kit that uses impala rotors and Camaro/firebird calipers with the E brakes. Very nice pieces and all the hardware to boot.
Ben