the motor will torque over if the motormounts aren't good enough, and the shifter will go with it, my mustang with a SHOT drivers side motor mount, would torque over so far that in first gear, my shifter would hit the passenger side of the console... other than that, there were no symptoms...
if your passenger side mount is shot, then you likely won't notice much of a problem, transmission mount, not too sure...
just make sure if you change your transmission mount, you don't put a solid in there, if you have rubber up front, good way to crack your tranny casing