My 2010 GMC Sierra 2500 came with factory backup camera and rear view mirror display. I recently added the OEM navigation radio and had an aftermarket shop do the installation. Everything works perfect except they did not know where the wires were located and which ones to connect / splice in to move the camera display to the nav screen. I've looked at a lot of forums but have not found this exact issue posted. Thanks in advance for any help you have to offer.