hi everyone new to forum and need help i have a 2007 tahoe 2wd ltz with on star voice command navigation bose system rear entertainment dvd but no back up camera. I have a black box and a white box under passenger seat that say bosch on them. From what i heard that most of the ltz were pre wired for back up camera can anyone help with this or direct me to what i need like harnesses camera to hook up to get it to work when i put the vehicle in reverse my nav screen says service rear vision system. I have talked to a couple of places and they told me 500.00 dollars to install system. any advice please