2000 528i vibration question
 

I have noticed lately when taking off from a stop a slight vibration from the rear of the car or the seat of my pants. It only happens when taking off from a start and is smooth throughout gear transition. The other day I had to jump on it from a stop and really felt it...I even heard the rumble from down below. Possibly center support bearing or flex disk?

Any suggestions?

Thanks,
Richard