How to stop your trunk from rattling
- Outdoor Foam(stuff that wont rot away) or thin rubber(get the rubber it saves on headaches),
- Masking tape or a crayon
- Doublesided tape if possible (makes job so much easier)
- Sheet metal screws
How To Do It
Find out where your rattling is coming from (specific locations at the tail light) use a crayon or tape to mark the places.
Take the rear tail light piece off (its got sort of yellowish white plastic wing nuts on the trunk hood)
In the places its rattling put the foam or rubber using the double sided sticky tape or just tape, stick a piece of rubber in place (make sure your not putting huge pieces of rubber down try to keep it less than 2 inches for the patches because if water gets in behind it might have a hard time getting out if you put big chunks and that might cause water damage or even worse yet RUST!) also put some rubber around the back of the plastic where the licence plate sits.
Put the tail light piece back on making sure you tighten it down till its snug.
The licence plate is one of the worst rattlers. Mark the holes at the bottom of the licence plate (GM forgot to put holes and screws in for it) and check the inside of the trunk so you dont hit any wires while drilling those holes. Take off the licence plate.
Drill a hole on each side of the licence plate. Drill all the way threw until you clear a piece of metal.
Put 4 pieces of rubber at the four sides where the licence plate sits and tape it to there. and put back the liecence plate.
Put original screws in the top two holes and put sheet metal screws in the new holes and tighten until tight.
There you are now rattle free from the taillights. Boom as loud as u want. If your spoiler or rack gives you any sort of rattle tighten it down (it already has rubber on it (or it should)). You might notice rattles all over your car now that the worst rattle is gone. :)