PAC OS-311B OnStar Interface (GM 24-Pin): * Replaces factory radio in 2003 - 2006 GM SUVs and trucks while retaining OnStar * Plug and play, no cutting or splicing into factory plug * Pacos2/Pacos2Bose communicates directly with the OnStar module to prevent false triggering and eliminating unwanted audio noise * On-board amplifier will drive two 4W speakers in stereo * Use with the existing factory speakers or external speakers * GM 24-pin