Filter Filters Sierra Remove All Filters Price $100-$500 (131) $500 and above (8) Condition New (139) Brand Harmony Audio (139) Make GMC (139) Compatible with 01-06 GMC Sierra Non-HD Crew Cab Truck Harmony R104 Dual 10"... $310.99 Compatible with 2007-2013 GMC Sierra Extended Cab Truck Harmony A102 Single... $324.99 Compatible with 01-06 GMC Sierra Non-HD Crew Cab Truck Harmony A122 Dual 12"... $405.99 Compatible with 2007-2013 GMC Sierra Ext Cab Truck Harmony A122 Dual 12" Sub... $481.99 Compatible with 2007-2013 GMC Sierra Crew Cab Truck Harmony A102 Dual 10" Sub... $424.99 Compatible with 2007-2013 GMC Sierra Crew Cab Truck Harmony R104 Dual 10" Sub... $308.99 Compatible with 2007-2013 GMC Sierra Crew Cab Truck Harmony F104 Dual 10" Sub... $479.99 Compatible with 1999-2006 GMC Sierra Extended Cab Truck Harmony R104 Single... $246.99 Compatible with 2007-2013 GMC Sierra Extended Cab Truck Harmony F104 Dual 10"... $395.99 Compatible with 1999-2006 GMC Sierra Extended Cab Truck Harmony A102 Single... $325.99 01-06 GMC Sierra Non-HD Crew Cab Truck Harmony R104 Dual 10" Sub Box & CXA400.1 $356.99 2007-2013 GMC Sierra Extended Cab Truck Harmony F104 Single 10 Sub Box &... $294.99 Compatible with 1988-1998 GMC Sierra Extended Cab Truck Harmony F104 Single... $254.99 1999-2006 GMC Sierra Ext Cab Truck Harmony R124 Dual 12" Sub Box Enclosure New $247.99 Compatible with 1988-1998 GMC Sierra Extended Cab Truck Harmony R124 Single... $246.99 Compatible with 2007-2013 GMC Sierra Extended Cab Truck Harmony R104 Dual 10"... $299.99 Compatible with 1988-1998 GMC Sierra Ext Cab Truck Harmony A122 Dual 12" Sub... $516.99 Compatible with 1999-2006 GMC Sierra Extended Cab Truck Harmony F104 Single... $264.99 2007-2013 GMC Sierra Extended Cab Truck Harmony R104 Single 10" Loaded Sub... $281.99 2007-2013 GMC Sierra Crew Cab Truck Harmony R104 Dual 10" Sub Box & CXA400.1 Amp $353.99 Compatible with 2007-2013 GMC Sierra Crew Cab Truck Harmony F104 Dual 10" Sub... $404.99 Compatible with 2007-2013 GMC Sierra Ext Cab Truck Harmony F104 Dual 10" Sub... $470.99 2007-2013 GMC Sierra Ext Cab Truck Harmony A122 Dual 12" Sub Box Enclosure New $245.99 Compatible with 1988-1998 GMC Sierra Extended Cab Truck Harmony R104 Single... $236.99 123456