I have found the REAL problem with the tailgate rattle. After years of frustration, I finally tried to adjust the hatch bumpers all the way down until you hear a ratcheting sound. Tighten the screws and Voila!!!. The noise is gone and hasn't returned for 3 weeks. The problem seems to be the bumpers being mis-adjusted at the factory maybe. This prevents the latch mechanism from fully seating in its closed position and allowing the latch to move sideways in its slot.