'89 560 sl w/ 160K, grinding noise from underneath center while moving, noise starts at about 10 mph. shifts without clunking and smooth, noise changes as you back off throttle, all wheel bearings greased and smooth, brake calipers cleaned and not sticking. thinking flex plate and/or center carrier bearing. what should I be looking for? any test? what does a bad flex plate or carrier bearing look like?
Thanks.