[AZKen]

After many years and many owners, you can't trust wire colors sometimes, so be sure they go where indicated.

Ignition switch wiring per 1965 GMC diagram: I do not see a legit 1964 GMC diagram.

1. Red to terminal "BAT. This is an "always hot" battery source.

2. Pink to terminal "IGN"

3. Violet to terminal "SOL"/"START". This wire comes from solenoid terminal "S"/"SOL"

4. Brn/Wht to terminal "ACC". This is part of the charge light (tell tale). It comes from the Voltage reg "L", goes thru the right side 6 pin, comes out as two wires. One BRN/WHT and one BRN. Brn/wht to ignition ACC as described and the Brn goes to cluster "G" which connects to the Gen Light thru the flex print.

5. A brown wire from "ACC" to fuse panel. The terminal it goes to has another brown wire on it that is jumpered to another terminal. Don't see another other way to describe. No number on fuse panel given.

The Dark Green shows on diagram from temp sender thru right side 6 pin, then to cluster "H" which connects to temp gauge thru the flex print.

Yellow from coil pos to "R" terminal on starter solenoid. Resistance wire from "R" to right side 6 pin. Comes out of 6 pin as a pink to Ignition switch as described above AND to cluster "E".

It's up to you to sort out the wires and be sure they go per diagram. If the colors match, all the better.
Report issues/questions before powering up. You are only using 4 out of 5 ignition switch terminals. I believe the 5th is GND, right?