GM part# 17801989B I have a brand new in the box exhaust system that fits both a 2007-2008 Silverado Crew Cab 1500 or Extended Cab short bed 1500 with a V8.... It fits either model. It is a direct bolt on application from GM. I'm sure it will work on the Sierra as well. Paid 500.00 for it last year, and would like to get 350.00 for it. If you go to your local dealer they will try to bang you for 900+!! Generic photo because I don't want to tear up the original packaging. Feel free to PM or email me for more info. firstname.lastname@example.org Ernie Wording from GM's Performance Accessory website: And a link to another site that sells the system. http://www.gmaccessorydealer.com/details.asp?prod_id=95366 Give the exhaust note of your Silverado an aggressive growl with a custom-built, single Cat-Back Exhaust System. Constructed of free-flowing, mandrel-bent, T304 stainless steel tubing with semi-polished muffler, System has a fully polished, dual-walled, 4-inch angle-cut tip. Features the Bowtie logo. For Crew Cab, 5'8" Short Box and Extended Cab, 6'6" Standard Box.