With my bad knees, it was too far to crawl out from under the car to get my rubber hammer. I just used what I had under there with me. Since both cats are mounted together, if you hit one, they BOTH vibrate, so using the screwdriver as a stethoscope remedied the troubleshooting problem.

Anyone find an inexpensive source for those stainless steel cat assemblies for the '98 C280? I really don't want to start cutting them up and then welding new parts together. Would rather keep it close to original.