It's hilarious how many times I've scared the bejeevers out myself when I heard a chair/toolkit/whatever sliding around my trunk. Scares me EVERYTIME I put something heavy in there... takes me a few minutes to realize... then I feel dumb all over again. But, I experienced the sound your speaking of (non-parcel related). Check that both the Sway bar brackets are not broken. Have you installed the recall brackets up there? Are bushing still seated nicely. It could be the sound of the bar banging against the frame as you stop braking. (does it happen just when you let of the brakes) A 'BOING' I found up front was a tie wrap I had used on something up there and hitting the spring and going PING (sounded like a bell). Hope it helps! James L 004009