[Boxtaboy]

At 58k miles, my car exhibited a vibration/grinding when taking right turns under power. At first I thought my differential was shot, but it turned out to be that my motor mount was shot, which allowed my motor to shift enough during turns to disrupt the drivetrain geometry. Once I had the motor mount replaced (which was clearly cracked after it was pulled out), the symptoms went competely away.

I would have your motor mount checked for cracking in the rubber.