Just returned from my adventure under the MH. Thankfully, I was wrong about the catalytic converter, and you guys were right about the heat shield (kind of).
Turns out it was a heat shield, but NOT on the converter. Actually I found two loose items. The first was a heat shield around the tailpipe where it goes up and over the rear axle. As you all stated, the heat shield had broken welds and was barely hanging on. I started to just remove it, but the tailpipe is very close to the bottom of the storage compartment, so I bought a couple of clamps as suggested and tightened it down. It was hard to get to, but I got it done.
The other loose item was where a tailpipe bracket had come loose (another weld) and it was just hanging there flopping around and making noise. I was also able to secure it with a clamp and now all is well.
Thanks so much for the information, guys. I am usually able to help other people by listing all the problems I have and sharing other people's expertise when fixing it.
My life is hard, but it ain't dull!!!