I had an opportunity to have the use of the lift again Saturday morning, and I put the Brick on the lift to recheck all the bolts and nuts related to the mount swap. Everything is still tight, but I did notice that the exhaust head pipe mount bracket looked a little strange. I loosened the nuts holding the pipe to the mid bracket, and the bracket moved quite a bit. I didn't hear the odd harmonic afterward, so I suppose that the new mounts had changed the angle of the pipe and bracket, stressing the exhaust system.

Bill