Pioneer and Alpine have a Nav. unit (Din style) for Gm cars, supposedly it fits right in where your existing radio was. These have Nav. XM and Ipod hookup, I would get an installer to do it for you so its done right. Been thinking about changing my Bose unit but I have XM built in and my Nav. is external Garmin...like the portable ones because I can use it in my wife's suv as well.