Chevy, on their website, shows the 2013 Silverado 1500 with the 5.3L/3.42 gears can 5th wheel tow between 8100 - 9600 pounds depending upon configuration (crew cab, short box, long box, etc.).
Go here to see the specs for a 2013 Chevy (or GMC for that matter). Got to page 10 to see the specs.
http://www.chevrolet.com/content/dam/Chevrolet/northamerica/usa/nscwebsite/en/Home/Vehicles/Trucks%20and%20Vans/2013%20Silverado%201500/Model%20Overview/02_pdfs/Trailering%20Guide%20MY13%20eBrochure.pdfEdit - Hopefully make it smaller so the whiners will be happy.