I still cannot identify the source of this rattle for the life of me, and it's starting to drive me crazy. Sure I can drown it out with music or RPMs, but that's not really the point.
So I had my buddy drive my car around while I layed in the hatch, and best I can tell the sound is coming from the rear panel (the one on the hatch itself that covers the third brake light). when I pushed on the large plastic cover, the rattles stopped, though I can't be 100% sure because it's not a constant rattle.
got home, removed everything, made sure EVERYTHING was tightened down, every nut, every bolt. the wire harness for the third brake light was sitting in there extremely loose so I electrical taped it still. put it all back together, sound is still there.
