I searched on the M.B sites and didnt come up with much. So im here to ask the offtopic members for some help. I have a 1990 300E, I want to replace my factory head unti with a aftermarket piece. Removing the factory unit shouldnt be a problem, but wiring a new one is. DOes anyone know where I can get directions to do this, or can any one of you guys shed some light on me for this procedure. thanks.