W108.018 1970 280 SE M130.980 with manual transmission

Back from before my head gasket leak presented itself I had a noise that sounded like a grinding coming from the transmission when I would drive 5 minutes or more over 80 mph. When I depressed the clutch the noise went away immediately and completely. The noise would also come in when turning left. Again going away immediately and completely when depressing the clutch. I suspect a bad throw-out bearing.
Brad