I brought my truck to a trusted mechanic and he was horrified at the way the truck drove. It turns out that my two u joints were ready to fail...a couple of the pieces were rusted completely off. The pinion nut needed about a 1/2 turn of the wrench. He couldn't believe how long I've been driving the truck this way....over three years. He had never seen a drive line so loose.
I got my truck back with two new ujoints and a tightened pinion nut....and it's like night and day the way the truck drives. I'm amazed. It's quieter, drives smoother, has improved acceleration and it feels like I'm getting the most out of my 283.