So update- was driving down to town and noticed the vibration was getting WAY worse so I stopped and turned around and headed back. As I pulled into the driveway, I heard a loud bang and then the familiar clanging of a dropped driveshaft. As I looked under the truck I saw the rear u joint had come free. The nuts had come off of the u bolt. The u joint seems ok but I didn’t want to take any chances. I replaced the u joint with new nuts and washers ( I checked the threads on the u bolts and they were in good shape). A quick test drive later, I realized that the increasing vibration was caused by the loose nuts/ possible u joint binding? It seemed to cure 96% of the vibration. When I looked at the u joints, I didn’t look closely at the rear nuts. When I wiggled them, they seemed tight. Oh well, another lesson learned. On to find the last small vibration (s).
