I bought a 1998 E300D with 99,000 miles on it a few years ago. I had the dealer change the transmission fluid and filter when they replaced the drive shaft under warranty. I now have 162k on the car and did another trans oil and filter change. Before the change the car would vibrate when put in reverse, both stopped and backing up, when cold. After the oil and filter change, it still does it. There were no particles in the pan, but the fluid was dirty and there was a fine coating of black on some parts of the pan, easily removed with a cloth.

Does anyone have any idea what's going on here?

Thanks and Happy New Year, Juergen