No backup wiring harness on truck

The truck is nearly show quality for its age. I purchased a new rear bumper with accent backup lights on the bumper. I went to connect the wires and found that there were none. I went back to the backup switch on the Mazda four speed transmission and discovered there is nothing there for wires. One of the previous owners has done some questionable wiring throughout the truck which I have tried to repair, but I have no idea what to do if there is no harness for the backup lights. Is there a simple way to create a wiring harness for this? I have looked at bone yards but none have a similar vehicle. I do not know what to do. I just purchased a new switch and pigtail but do not know what to do from there. Randy