Rear Axle Questions

[JCook5003]

im in the process of installing a 258/T18/D20 setup into my 1978 J10 that came originally with a 360/TH400/Quadratrac setup. in the donor 1974 truck that I pulled the motor and transmission out of the rear axle looks more centered than the rear axle in the 7 Quadatrac truck.

I plan on installing a 6" all spring lift and running 37s. Will the offset axle be a problem? Do I need to swap the axle from the donor truck? so it's more centered?

Thanks
Josh

[Cecil14]

As far as I know (or thought I knew) all the J-truck rear ends were the same offset, both D20 and QT. You should be fine, but you'll need to measure your angles ultimately to know for sure.

Long bed or short?


aa

[JCook5003]

Long Bed

[Cecil14]

Typically the really long rear shaft from the long beds offsets the angles generated from a lift. There are obviously extremes out there, but most of the time the angle ends up being fine.

Again...to be 100% you'll have to measure everything once you get to that point as every rig ends up being just a little different.


aa

[Stuka]

Yeah, rear axle for J-Trucks were all the same, regardless of t-case. Year for year of course. 80+ are all centered.

[REDONE]

Yeah, rear axle for J-Trucks were all the same, regardless of t-case. Year for year of course. 80+ are all centered.

This is absolutely true from everything I've seen in the FSJs I've owned AND seen in the parts yards. I currently run 5" of lift and the rear angles have only gotten better since I've been able to shim the pinion going up. The offset CLEARS the fuel tank, and that's the only benefit/detraction worth mentioning.