Is this a long bed? If so, did you put gear oil in both balls where the u-joints are?

You could have heated things up to the point they expanded and locked up causing your failure.

Take some photos if you can.

Also can you push the truck in neutral? If so push it around (with a few buddies, safety first!!!) and listen for noise.

SWEET
Sergeant At Arms: Old Dominion Stovebolt Society
BUNS?!?!?!Where we're going, we don't need no buns.....
1950 GMC 450
1951 Chevy 1/2-Ton
The GreenMachine
In the Stovebolt Gallery