check the drive shaft for proper phasing. on the section that has the slip yoke if you sight from one end to the other the caps should align perfectly
if it had been towed and the drive shaft removed some wrecker operators will just separate the shaft at the diff and pull the sections apart and the mechanic at the repair shop may have put it back together wrong also could be a bad carrier bearing, bent drive shaft, bad ujoint or incorrect drive line angles
may not be the problem but it's a place to look at