im new to the 4x scene and live in alaska where it gets real dark in the winter and stays light all the time during summer. we are now approaching winter and ive been having a hard time backing up with the darkness this time of year. i recently purchased some tractor lights that have a positive and negative wire sticking out of it. how can i wire these into my 1990 chevy 1500 so they light up automatically when i shift into reverse? any hints or help would be greatly appreciated. thanks