My son bought a 12 Dodge Charger, (Charger SXT with blacktop package..... I want to add a MOPAR back up camera as a gift but the web site says it must have a compatable radio "Production Back Up Camera system that integrates into the Back Up camera ready radios (CTP RE2 or RE4 only), includes camera, wiring and instructions" How do i know if his radio is a RE2 or an RE4 system? The radio he has is a Uconnect(R) 8.4 CD/DVD/MP3/SD Card Input with 8.4-Inch Touch Screen Display