Metra 71-1858 Reverse Wiring Harness for Select 1987-2005 GM Vehicles Reverse Wiring Harness for Select 1987-2005 GM Vehicles 21-Pin plugs into OEM Radio Power/4 Speaker Harness is designed to plug in the factory radio Can be used to repair a harness where the plugs have been cut off or damaged For 1987-2005 GM models, power for speakers