Joe my truck has the torque tube so the pinion angle is fixed. The only change I did to the drive line was to put in a new bushing and seal in the tube which meant unbolting my u-joint. However this problem was there before I did that work.
Now here is another neat thought which arose after you mentioned seat of pants. I do know that my seat cushion is quite springy as I bounce a good bit on a bump. But when someone is driving behind you and mentions the truck is going up and down it is more than the seat cushion.
