Radio replacement for gm LAN 29-Bit vehicles/ the Crux SOCGM-18 retains general motors factory-featured safety and warning chimes -for installation of After-market radios. It provides 12 Volt Accessory Output (4 amp), including RAP (retained Accessory power), illumination Output (2A. Max), telephone negative mute trigger (Output to new stereo), low voltage (battery run-down protection), and adjustable Chime volume.