Filter Filters Sierra Remove All Filters Price $100-$500 (131) $500 and above (8) Condition New (139) Brand Harmony Audio (139) Make GMC (139) 01-06 GMC Sierra 1500 Crew Truck Harmony F104 Ported 10" Sub Box & CXA400.1 Amp $274.99 01-06 GMC Sierra 1500 Crew Truck Harmony R104 Ported 10" Sub Box & CXA400.1 Amp $261.99 Compatible with 2001-2006 GMC Sierra HD Crew Truck Harmony F124 Dual 12" Sub... $526.99 Compatible with 2001-2006 GMC Sierra HD Crew Truck Harmony A122 Dual 12" Sub... $496.99 Compatible with 2001-2006 GMC Sierra 1500 Crew Truck Harmony F104 Ported 10"... $234.99 Compatible with 2001-2006 GMC Sierra HD Crew Truck Harmony R124 Dual 12" Sub... $326.99 Compatible with 1999-2006 GMC Sierra Ext Cab Truck Harmony A102 Single 10"... $404.99 Compatible with 2001-2006 GMC Sierra HD Crew Truck Harmony A122 Dual 12" Sub... $410.99 Compatible with 2001-2006 GMC Sierra 1500 Crew Truck Harmony R104 Ported 10"... $216.99 Compatible with 2007-2013 GMC Sierra Extended Cab Truck Harmony A122 Dual 12"... $395.99 Compatible with 2007-2013 GMC Sierra Crew Cab Truck Harmony A122 Dual 12"... $541.99 Compatible with 01-06 GMC Sierra Non-HD Crew Cab Truck Harmony A122 Dual 12"... $491.99 Compatible with 1999-2006 GMC Sierra Extended Cab Truck Harmony A122 Dual 12"... $430.99 2007-2013 GMC Sierra Crew Cab Truck Harmony R124 Dual 12" Sub Box & CXA400.1 Amp $386.99 Compatible with 2007-2013 GMC Sierra Ext Cab Truck Harmony A102 Dual 10" Sub... $465.99 2001-2006 GMC Sierra HD Crew Truck Harmony R124 Dual 12" Sub Box & CXA400.1 Amp $377.99 Compatible with 2001-2006 GMC Sierra HD Crew Truck Harmony F104 Dual 10" Sub... $410.99 Compatible with 01-06 GMC Sierra Non-HD Crew Cab Truck Harmony A102 Dual 10"... $484.99 Compatible with 1988-1998 GMC Sierra Ext Cab Truck Harmony A102 Single 10"... $389.99 Compatible with 2001-2006 GMC Sierra HD Crew Truck Harmony F124 Dual 12" Sub... $440.99 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 R124 Dual 12" Sub... $336.99 Compatible with 2001-2006 GMC Sierra HD Crew Truck Harmony R124 Dual 12"... $356.99 Compatible with 2007-2013 GMC Sierra Extended Cab Truck Harmony A102 Single... $399.99 123456