Mike, if the clunk sounds like it might be due to the driveline torquing over toward the driver side when shifting to D; you might try the following:
- Double-check the motor and tranny mounts for correct type and mounting - you never know.
- on my car the exhaust pipe can bang against as cross member brace when the driver-side mount sags a bit. Any close-fitting exhaust pipe could be the culprit.
- If yours has the little shock absorbers mounted next to the motor mounts, these don't have much travel, and can actually bottom out if there is anything amiss with the motor mount height, like sag, or the wrong mount.
makes a great clunk when shifting to D - ask me how I know.

Get someone to shift the car from R to D a few times while you watch and listen under the hood. Drive the car and punch it in low gear and listen for the clunk as the engine torques over to the right.

If it's really coming from a delay in the tranny, then not much you can do externally.

DG