[biketopia]

Originally Posted by Richard

Your driveline is not correct. You cannot run a fixed shaft between the carrier bearing and third member. Even if you adjust the bearing to take stress of it while static. The rear axle moves forward and back as suspension cycles. This true on both leaf sprung and coil (trailing arm) suspensions. A fixed shaft can be run between the carrier bearing and transmission. There should be a slip yoke on the rear shaft.

Exactly this, you need a slip yoke on the rear shaft. Contact a local driveshaft builder and they will provide you with a sheet of all the measurements they'll need to build you a new shaft. Or drop off the truck with them to have one fitted, either a one-piece or two-piece with slip yoke will work. With a one-piece, you will likely need to remove the carrier bearing support.