what is it that would cause the exhaust system to make a rattling noise on 1999 Chevrolet Suburban 1500

It sounds like something inside the converter is loose, is that possible ??

Yes it is! Most likely the catalyst inside the converter!
Thank you wetry for responding to my question. I suppose that means that it would have to be replaced ?? and thank you for your time..
You R welcom, yes it will perform better and that means more mpg. Visit a muffler shop, will save a buck or two cause there are aftermarket converters that work quite well.
Once again, I thank you for your help and time.. This really is a great site for someone like me to have access too..