Does anyone have a GM style Catalytic Converter? I need one for my 81 for my restoration. Any thoughts?

If I were you I'd put on an aftermarket high flow cat, Dynomax, Flowmaster. I know you said restoration but this is one place I'd go with a non GM part unless its a concourse car. GM cats are too restrictive & rob hp. In short they SUCK (imo). See Ya John

Thanks for the info, but I am doing a concourse car. I've got to keep looking!