Don,
I think you have a firm grasp on how the coil circuit works...
The key side of the coil (+) needs at least one wire, obviously. It might need two. It would depend on how your truck was wired and if the coil has a internal resistor.
If you have a start/run resistor on the firewall, and it only has one wire going to the coil, then the coil + should have two wires. The other wire will come from the starter solenoid.
If you have no ceramic resistor on the firewall, then the coil will have only one wire. This wire should come from the key switch.
These are FACTORY wires...tachometers and other items might add wires to this post too..I don't know.
Stuart
