im a newb to this site, sorry in advance if someone posted this on and earlier thread.

i recently bought a 1992 sc400 with 209K and when i get to the freeway and go over 65 and let go of the gas i hear this loud grinding noise inside. everything feels good, power, all that stuff. but one thing is that the car shakes at the lower rpm(when i rev it, or when im cruising at like 2K rpm.) if someone might know the answer please help me out.
thanks in advance.
Also i recently noticed the steering wheel shake on the freeway to like at 65.