Where can I buy a Chevy Avalanche rear bumper?

Today my 2002 Chevy Avalanche 2500 rear bumper cracked, dont know if it was from the cold or a snow pile. Anyway the crack is right above my exhaust and I have straight back dual exhaust. It has the cladding around it and the bumper is plastic I am having a tuff time finding a replacement. And I dont want the steel bumper, I am looking for the stock plastic one. If anyone knows of anywhere I can purchase one that would be great!