I'd be willing to bet it's the little bushing on the linkage that goes to the transmission. I had the same problem with mine - a rattling/buzzing sound at certain RPM's. I rolled under the car and sure enough, the bushing was totally missing.

I installed it with a screwdriver and a pair of long nosed pliers.

P/N 202 992 00 10

If you can move the shifter lever fore/aft about 1/4" inch while it's in the "D" position, the bushing's gone.

I think the proximity to the exhaust causes it to harden up and break apart. It's only a buck, I bought a couple for spares.

__________________
-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250