I have a 2000 ML 320, purchased in April this year, coming off of a lease.

I have not had any major problems, outside of the steering rack being replaced under warranty, because of a "popping" noise when turning the steering wheel when the vehicle was stationary.

I do have a "plasticy" sounding rattle which seems to be coming out of the passenger side a/c vent in the dash. It sounds like a baby's rattle, or perhaps a stack of plastic lunch forks jiggling around, every time I am on a gravel road (constant) or tar strips, or railroad tracks (intermittantly, consistant with the sudden jolt of crossing the tracks)

It does not seem to be the vanes in the vent. Nor is it effected by opening or closing the vent. I have looked into the vent with a flashlight and see nothing.

There is a wealth of information on these boards, so I thought that I would ask here, before I take it to the dealer. I would rather try to fix it myself, rather than having to deal with the "unable to duplicate" routine.

Does anyone have any guess as to what might be causing this?

Thanks!
George