hey all. i need some help with figuring out what could be makin this noise. First off, i have a 94' Z28 with an A4. When my car gets goin down the road you cant hear anything, but when i get to my first stop i will start hearing a really loud rattling/knocking from underneath, and cant figure it out. I switched through gears and only when in NEUTRAL did the rattling stop, then back in drive it starts up again. When driving you can barely hear it, which is probably just due to the loud exhaust. anyone know what the heck this could be?