740GL wagon with 240k miles. Car has been serviced regularly, and performs well for the most part. Engine is tight and full of pep. Trans works fine, but did have delayed shifting problem a while back. Replaced motor mounts and corrected this. Have exchanged trans fluid at regular intervals. Current problem started with driveline vibration and noise. Replaced trans mount and noise and vibration was worse. Replaced center bearing bushing and bearing [bearing okay, but replaced while renewing bushing which was bad]. No more vibration, just noise which I do not like. What should I do to correct?