A few possibilities:
Check the U-Joints they may be dry, loose, or going bad.
Clean out the rear spring pack with water (high pressure if possible) then blow Graphite into the spring pack (Usually available at auto parts stores, but I've been know to shave a pencil down when I'm out).
Check the torque on the rear spring hangers and the U-bolts (lube the bushings with graphite).
Check the rubber exhaust hangers (again graphite works well to lube the hangers, oil breaks down and deteriorates the rubber).
Check the U-Joints they may be dry, loose, or going bad.
Clean out the rear spring pack with water (high pressure if possible) then blow Graphite into the spring pack (Usually available at auto parts stores, but I've been know to shave a pencil down when I'm out).
Check the torque on the rear spring hangers and the U-bolts (lube the bushings with graphite).
Check the rubber exhaust hangers (again graphite works well to lube the hangers, oil breaks down and deteriorates the rubber).
