Car Goes Clunk

[rastaman190e]

Hello:

I have a 190E 2.6, 1993 with 125K miles. It is running fine but I am a perfectionist and want to make sure all is well. Here is my issue: i hear a clunk sound when I move the selector from park to drive. Now, this only happen if I allow the car to roll back (little roll) when I park it. The sound is not there if I keep the brake pedal depressed, engage the parking brakes, move the selector to park and turn the car off. What could be causing this?

I think the fisrt question that should be asked is: should my car roll back -little roll?

Note that I replaced the front and rear flex disk at 99k and visual inspection with some pulling/pushing shows both of them are fine.

Thanks