I read this one old post about fixing that annoying buzzing in the passenger's side of the dash. I pulled mine apart yesterday and fixed that buzzing knee plate thing. But I also found another thing that was rattling like crazy. If you look to the right of the dash, at about the same height as the metal knee plate there is this white horse shoe shaped thing that was rattling like crazy. I put a couple dabs of silicon on it and it's mounting and voila! no more rattle. I do not know what this thing is, but it attaches to the side, just above the side kick panel and is around 4" x 4" and shaped somewhat like a horse shoe. It is white plastic. I also took the time to cable tie some of the wiring harnesses and to put foam rubber around them. Anyway, I put the thing together and now it is nice and quiet. No more rattles and no more metallic buzz.

 

Good to hear the rattle is gone. Next time it would help to take pics. Will have saved you all the hassle of trying to explain how that piece looks like