Larry, did I not see that you have a GMC or are you screwing with me. If you look under the rear of the your truck you will see a square connector. It should have 4 seperate connectors in it. If its like mine there should be 2 lite blue wires in 2 seperate connectors. they are the turn bulb wires. I spliced in a wire from each and installed a seperate 4 prong trailer connector by the Horn wiring plug (7 wire). Ran the wires up through the front cover under the bedroom. If you take the front compartment door latch (hold open) and the pin box trim off you can pull the wires through with 2 coat hangers or a long stiff wire. Then I ran them inside the wire harness that runs down each side. You will have to remove the screws from the lower skirting to run the wires. I did use split tube to protect the wires. You might want the run a wire for back up lites while you running wires. Inside of the electrical box on the pin box there is a blunt cut wire for back up lites. Yellow I think. CRS setting in. I could post pix if you like. BTW, since you are adding things to your sig and screwing with me...its "I" before "C" except after "C" (view)
Bob