Hey Bill, when I bought the truck, it vibrated like heck for the 5 hour drive home...previous owner said it was the driveshaft, he was right mostly...I had that replaced, turned out the old one was once a two piece , but someone cut out the middle joint and welded the two halves together, they didn't do it quite straight. It still vibrates but not near as bad. The shop that replaced my driveshaft also replaced the u-joints, and said that the rear end needs work. The yoke that connects to the driveshaft from the rear end (sorry for the lack of technical terms) feels loose if I grab it and shake it. Maybe it's a worn bushing or bearing? The wheels were recently replaced, it does this with the old set and with the new.
