I have an 06 Sierra Denali with the stock 6 disc changer. I was wondering if it will work with the AVIC-Z120BT? Also is there any way to retain the rear seat entertainment which included an overhead dvd player and wireless headphones. Also have the back seat audio controls on the back of the console. I know the onstar, bose, steering wheel controls, and xm radio will work with the right harness but not sure about the others. Any help would be much appreciated.