Attributes . 1999 to 2006 Chevy Silverado 1500 Ext. Cab, 1999 to 2006 GMC Sierra 1500 Ext. Cab, 2001 to 2004 Chevy Silverado 2500 Ext. Cab, 2001 to 2004 GMC Sierra 2500 Ext. Cab, 2001 to 2006 Chevy Silverado 2500 HD Ext. Cab, 2001 to 2006 Chevy Silverado 3500 Ext. Cab, 2001 to 2006 GMC Sierra 2500 HD Ext. Cab, 2001 to 2006 GMC Sierra 3500 Ext. Cab, 2007 Chevy Silverado 1500 Classic Ext. Cab, 2007 GMC Sierra 1500 Classic Ext. Cab, 2007 GMC Sierra 2500 HD Classic Ext. Cab, 2007 GMC Sierra 3500 Classic Ext. Cab . Names