Truck Repair: 2000 gmc sierra, gmc sierra, clunk

Question
Ive just replaced my u-joints to take care of a clunk when shifting and a vibration starting at 50 mph when accelerating.the clunk is fixed but the vibration is still there. Any suggestions? thanks

Answer
Hello Chris,
Be sure you installed the "C"clips in the u joint caps in the rear diff yoke.
Any chance the driveshaft is bent?

You might jack the rear up and have both wheels off the ground, and run it in gear while watching the driveshaft.

Van