steves66c20,
Here is a neat site that has wiring diagrams for your year truck....although it's a GMC! I don't know if they are similar, but this shows backup lights, colors, connectors and a firewall plug location.
Backup lights normally require a linkage or transmission operated switch to 'turn on'..I guess you have all the in place.
There is another Chevrolet site I checked, but they don't show backup lights on their wiring diagrams...looks like they were installed with a bumper, or after the truck left Detroit! The wiring on the Chevrolet site looked almost identical to the GMC site, sans lights and wires.
http://community.webshots.com/album/76722164VVgaQA Stuart
