We have the same muffler

I feel the bond now...

I had a vibration when I lost a u-joint, but only under acceleration. Started as a sense that something was amiss, of course the warden could never feel it, then as it got worse I could definitely feel it in the floor, and it would make my champagne glass vibrate just a bit. All the joints seemed tight... I just ran it until it got bad enough to show itself.

 

Found the problem. It was the middle u-joint on the rear driveshaft. Had to remove the driveshaft to find it, but the u-joint had a stiff spot in it. Replaced u-joint and all is well. $43 for the dang thing! Can you believe it?