Scosche SHGM03B Universal Speaker Harnesses Compatible with 1985 and up General Motors Multi-Color. Scosche came to life in 1980 when Roger and Scotia “Scosche” Alves started a car audio consulting business in their garage. Scosche’s truck and car accessories aren’t just innovative and user friendly – they’re fun! Enhance your driving experience with a wide range of car and truck accessories including the multi-award-winning MAGICMOUNT family of magnetic mounts for safely securing and displaying your mobile devices.