The new mount made the 600 mile trip I took this weekend much quieter, until one of my front motor mounts tore through allowing the mount arm to vibrate against the body. It sounds like the car is coming apart when I shut it off and the engine gives its final shudders.
I think the problem was caused by oil on the motor mount, and the fact that it was slightly misaligned and "tweaked" for two years with the incorrect cross member in the car. The mount was only two years old.