This Worked Well For Me...

[robz02alero]

I disassembled my trunk this morning, particularly the plastic braket that holds the license plate frame that attaches to the trunk. There are 5 or 6 screws that screw into brackets on the inside of the trunk and then 2 nuts on the left and right side, this is how I removed the plastic piece. (it was dirty as hell under there too so it gave me a chance to clean and wax underneath there) I used 3M doublestick tape where there plastic piece meets the upper half of the trunk as well as the very bottom part of the plastic where it meets the trunk and it work real well at killing that rattle. I also applied weatherstriping to the back of the license plate and then screwed it back in place. In addition I used clear silicone and filled in all the gaps around the inside and outside of the trunk. It made a hell of a difference with the thump in my trunk. Sorry I didn't post pix and I don't know how many of you have already done this but if it helps one of you out there then it's worth it.

good tip, that panel is the only piece on my alero that makes rattle as well.