I just put a deposit on a 2012 300-S. I was under the impression that the backup camera was part of the 8.4" package. I knew the Garmin navigation was an option. I found a car that had the dual moonroof and Nav, but then as I was walking around the car, I noticed there was no camera in the 3rd brake light housing. I see I can get the camera kit but it says it's only compatible with CTP RE2 or RE4 radio units. How do I know which radio my car has? This is an option I was looking forward to having. Along with the Garmin nav. I could live without the dual pane moonroof. The rear window shade would have been nice also. :-(