I know this topic has been brought up before but no one seemes to have found a conclusive answer. I recently bought a 2007 Ram 1500 quad cab, 2wd with 4.7L enginge. It vibrates between 63mph & 80mph. Also, the drive shaft makes a wierd noise when you shift into reverse. Most of the vibration is felt in the seat. At 70+ mph I can shift into neutral but the vibration is still there. It also happens whether I'm hauling something or not. Any new thoughts on the matter?
Remove the drive shaft and inspect the universal joints for stiffness or bearing failure.
You can't just look at it you have to physically remove the shaft and inspect the joints.
The vibration is probably happening because the bearing is worn or the joint is frozen and can't move.