On Sale! Dual Sub Box (behind rear seat)2001-2006 GM SIERRA HD CREW Xtreme Enclosures $199.95 $201.15 $139.95 Fits 2001-2006 Chevrolet Silverado / GMC Sierra Crew Cab Heavy Duty 1500, 2500 AND 3500 Series Truck Note: ( FITS ONLY HD MODELS ) also fits 2007 classic body crew Fits two 8 inch or two 10 inch subwoofers Fits behind rear seat Mounting Depth = 6 inches... Choose Options