I'm swapping in an HEI on my '65 really soon. I assume your truck has a 12v system but the points distributor gets reduced to 6v. If that's the case, run a 10 or 12 gauge wire from a keyed source such as the ignition switch or fuse panel, etc. and that's it. If you're wanting to run a tach, run a wire to the "Tach" terminal on the coil. Of course you'll need to wire the rest of the tach, but that I'm sure you already knew
If you already have a tach installed, just run the existing tach wire to the "Tach" terminal on the coil. Don't forget to re-gap your plugs to 0.045.
