This article is from the Chrysler-Plymouth-Dodge FAQ, by Dr. David Zatz with numerous contributions by others.
Christopher Sennett Homer: Under the rear hatch are
two black plastic screw things with rubber bushings on the bottom,
at the rear corners on the hatch. When the hatch is closed
it rests on these bushings, now if one, or both, of them are too short
then the hatch pivots on the latch and rattles, so take some pliers
and unscrew the plasic bushings a little to extend them. that should
clear up that hatch rattle.