Everytime the cars enters a driveway or street where the chassis is made to change elevations there is a noise in the trunk that appears to be coming from under the package shelf. The noise sounds like something on the end of a shaft that is balanced in the horizontal position, and the rocking that occurs when you encounter different levels of pavement make the thing on the end of the shaft hit something very lightly once or twice. Very unusual.

I think the trunk assist torsional springs run through that general area you are talking about, maybe they are hitting on something or each other.

Previous owner wasn't named Hoffa, was he??