Heavy Hauler Diff swap

[crazyjeenyus]

I wanted this thread to cater to all those interested in diff swaps for any year / model heavy hauler.

My specific question I want to throw out for comments:

I’ve got a beautiful ‘67 C50 with a 167” wheelbase. My overall intent is to shorten the frame to fit an 8’ pickup box. I would also like the truck to be able to drive on the highway in a half-decent manner.

I also have a ‘75 C30, and I’m thinking about taking the diffs & drivetrain (get rid of the two-speed rear axle) from and putting on the C50.

Both trucks have the heavy duty ‘sm’ 4-speeds, (sm-420 on the ‘67, and sm-465 on the ‘75).

If there is anyone out there with experience on this, your comments are appreciated.

Also, if I swap the rear diff from the ‘75 C30 onto the ‘67 C50, I could theoretically mount it anywhere in the frame this eliminating the need to remove frame between the front and back wheels, and would just have to cut excess off the rear. Also, theoretically should be able to use axles and steady bearing from C30 also and not have to get a custom driveshaft fab’d up.