Well, we are going to take the plunge and upgrade the head unit on our 3500 SL. We are leaning towards the 7200NEX or 8200NEX - but I would like to keep the factory camera. Has anybody determined which wires feed the camera input on our existing radios? One of the installers at Best Buy said he always can grab those lines, solder on RCA connectors and use the factory camera. Hoping to do the same, but I don't have a detailed schematic of the radio to guide. Appreciate the help! Creger