Mike:

I had a rattle in my car and it was due to the front exhaust "muffler" rotting out on the inside and having loose metal parts in it. At certain rpms, it would rattle like that. Check the front exhaust muffler to make sure its not from there. Another option might be the A/C belt pulley. Belt may be too loose and hence the pulley is rattling.

Let us know what you find out!

-=>Raja.

__________________
1983 MB 190E, bought from Germany and shipped to the US in 1986.