2004 GMC Sierra OE Wiring Harnesses & Stereo Adapters GMC Sierra 2004, Aftermarket Radio Wiring Harness by Metra®, with OEM Plug and Amplifier Bypass. For aftermarket stereo. Metra preassembled wiring harnesses can make your car stereo installation seamless, or at least a lot simpler. 04 gmc sierra harness | eBay 04 GMC Sierra 2500 179k 6 4x4 LLY Right Front Door Wire Harness Window Lock. Right Front Passenger Harness CREW CAB. Pre-Owned. $96. Was: 1 product rating - Aftermarket Radio Stereo Install Dash Wire Wiring Harness Cable OEM Plug Adapter. $6. FAST 'N FREE. Buy It Now. Guaranteed by Tue, Jun. 4. Free Shipping. 421 Sold 421 Sold.