This is what fixed my vibration.

[richman513]

I was getting a good amount of vibration mostly when accelerating but sometimes when coasting at fast speeds. Accelerating from about 38-42 was the worst. Bad again at around 70. Rear u-joint on rear drive shaft was locked up. Replaced both and the vibration is gone. Just wanted to share my experience. Dealer said to use heavy duty non-greasable (lifetime warranty) cause the ones with grease fittings are junk.

03 Ram 2500 Hemi 4x4

 

[46RamMan]

I think the dealer is trying to sell you a bag of poo !!!

 

[pacofortacos]

In my experience the non-greaseable ujoints are superior to the grease kind - I only use non grease fitting ujoints but do make sure there is sufficient grease in them prior to installation.