the end of the tailpipe on my son's 2004 4 door lx automatic moved a few inches toward the center and started hitting/vibrating against the cutout in the the rear bumper. i cut off a few inches of the tailpipe so it now doesn't hit it.

why did it move over? I checked the exhaust hangers and pipes, nothing is broken or loose? car has 130k. is a motor mount or transmission mount broken?

 

It has to be the rear hanger. Re-check the metal tab attached to the exhaust, the rubber hanger and the metal tab attached to the car body.

 

Check the tube going into the muffler for rust?

From the back and sides, my muffler looked fine right up until it rusted through around the inlet pipe. When it did, the front dropped down a little and the tail pipe pushed into the bumper cover, melting it.

Any movement at the engine or tranny won't be enough to notice at the tail pipe. Whatever the problem, it will be near the muffler.