I don't know where you got that harness, but my cheap $100 kit from Chevy Duty has ends and numbers. Get the grommets if you haven't already, or the sheetmetal will cut the insulation.

If you're willing to name the source, it will act as a warning to others. smile

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.