I am pritty sure the drive shafts were out of phase when I got the truck (used) took it to a shop had is phased I was right. did the joints and hanger brg. started to get a drive line vibration between 40 and 50 about a rear ago. changed the u-joints all good. starting to get a slight vibration again. I could be anal though, My friend call me the prince and the pea cuz I felt a small stone stuck in my tire.