I have a nice 1982 300sd with about 120,000 miles and have recently started to experience a dull clunk in the driver front wheel well. The clunk happens when I back out of the driveway and simultaneously turn the wheel counterclockwise to the fullest. I can recreate the clunk at a stop when I turn the steering wheel counterclockwise as well. I can lightly feel the clunk through the floor and brake pedal.

Any suggestions?