[Mr. Esprit V8]

Can someone please advise on the difference in sound between a rattling cat vs. a rattling heat shield on a V8? Better yet, can someone please post a picture of heat shields on a V8, so I know where they are?

I have a rattling sound -- sounds like marbles in a can -- and I'm thinking it's the $$$ cat that needs to be replaced. I'm going for aftermarket high-flow cats. But I don't want to spend the money if it's just the heat shields.

Thanks in advance!