Stereo Antenna Harness Adapter for Installing a New Radio Into a GMC, Sierra, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006 Antenna adapter for installing a new Radio into a GMC SIERRA 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006 CarXtc adapter plugs directly into the antenna wire beyond the radio found in a SIERRA Plugs directly into your vehicle radio antenna harness behind the factory radio. Antenna adapter is needed for your GMC SIERRA 95, 96, 97, 98, 99, 00, 01, 02, 03, 04, 05, 06 If installing an FM modulator you will need this and the reverse antenna adapter