so for about a month now:

at a start from stop i get a clunk when i hit the gas. (no noise) just clunk.

and once i hit 65 70 mph i start getting vibration. cant do 80 my turck feels like its going to come apart. i am guessing its teh u joints. dont think its the tires as they would vibrate all the way through. speeds.

 

sounds like u-joints to me, you might want to check the carrier bearing also (if you have one)

 

Careful driving fast - or at all until you check it. You may lose the driveshaft on the ground and turn your truck into a catapult... or at least waste the shaft.

 

easy way to check... slide underneath and see what kind of play is in the shaft

 

make sure it's in neutral & wheels blocked

 

Look for rust colored dust around the caps. Bad joints can still feel tight.