Sounds ghetto, but if you absolutely HATE the back dash rattle problem... two solutions can KILL it entirely. obviously, weather stripping under the third brake light helps tremendously. but in my car, i had the corners of the dash liner literally JUMPING like 2 or three inches off the back dash, so i took some 1 inch long #8 sheet metal screws, spaced them out about 12 inches and sunk them in along the perimetter of the dash liner... it killed ALL of my rattling... and considering i'm too cheap to dynamat the back dash and see it as a waste of good material to do so, spend the 4 bucks, buy a box and start zappin screws... it works. will have pics soon.

peace