When I pulled out the stock Delco/Bose HU out of my 2004 C5. There was the standard GM Harness (has the power and speaker wires). But there was two additional smaller harnesses plugged in. What were these for. My only guess is they are the wires for the optional 10 disk CD changer that goes in the trunk, that I do not have. Am I right or are these for something else?