Gears & Axles - 12 bolt rear swap(NEED HELP)

i found a 12 bolt rear(3:73) outa a 77 truck ...with the same axel width and my TA.....but of course it is set up for a leaf spring set up ..but i >???? is ..how hard would it be to make the rear end bolt straight up...welding is not a prob with me im icar certi.....bt i just want this 12 bolt do to that it is a beefy one with the big pinion bearing and not the small pinion bearing...but just wondering if any one has done it...

Justin Reynolds

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Moving...

Tony.

If you can figure out how to mount your torque arm to that rear end you will be most of the way there.

Good luck on that one.........let me know how it goes.

You will need to do alot of work to get it to fit. Your spring perches, sway bar, shock mounts, LCA's, and last but not least your torque arm. I don't think it will be worth your time and effort. Never heard of anybody doing that anywere, Goodluck if you decide to do it. Take pics.!

You will need to do alot of work to get it to fit. Your spring perches, sway bar, shock mounts, LCA's, and last but not least your torque arm. I don't think it will be worth your time and effort. Never heard of anybody doing that anywere, Goodluck if you decide to do it. Take pics.!

Agreed. I think you'd be getting yourself deeper in that you think.

Plus, if it's out of a '77 truck it could probably use a rebuild anyways.

What size ring gear does your current axle have? If it is the 8.5" 10 bolt then leave it. The 8.5" 10 bolt has larger pinion bearings then the 12 bolt with the same size shafts. If you want to beef it a little, swap in some alloy shafts along with a Tru-trac.

Way too much work there to get that to work. The obvious no torrque arm provision is a biggie.
The worse problem is the truck 12 bolt is a wider track vehicle than a F-body. You would need to shorten the axles & axle tubes. That right there takes the cheaper cost intially & tosses it out the window. Not to mention if you want to retain ABS, & the OE style disc brake set up. Each of those would require modifications.
There is more here than meets the eye.

Not to mention that the "Truck" 12 bolt is about as strong as the 7.5". Afterall, they share damn near the same pinion shaft diameter... and with that, the ring gear diameter doesnt make a difference.

s&w race cars makes a torque arm mount for 12 bolt rear housings

That would make things so much easier if 12bolt truck rear ends were interchangeable with fbodies.

If your car is disc brakes how are you gonna switch to drum?