I don't know how long your truck is, but I had wire left over from the Chevy Duty kit on my 19.5' panel, and I had to route the wires up into the body to reach the taillight pods. If the wires are too short, it won't be by much.

1955 First Series GMC 250 1-Ton Panel
In the Gallery
Mr. Hedgehog - Follow the build
If you can't laugh at yourself, I'll laugh at you.