one way to solve it (what I did before I got my spoiler and removed my third brake light) was get a piece of hard foam, cut it out into kind of a wedge, wrapped it in electrical tape it isn't noticeable against the tinted glass, and wedged it between the rear windshield and the top of the third brake light....
even tho I have raammat installed on my rear deck, it still rattled, and this fixed both the third brake light from rattling anymore, and also stopped the particle board from rattling....
now that I've removed my third brake light, the board has started rattling again and its pissing me off, but I haven't had the time to take care of it yet
