That 5th pin was for a cold start retard or something eliminated 20 years ago. The new ignitions don't even need that 4 pin ballast resistor anymore. If you look at the wiring for the electronic ignition kit, the 5 ohm side of the resistor doesn't go anywhere. You should use the 2-pin ballast resistor that came with your coil and plug the 2 connectors in with the DrkBlue and Brown wires.
Rob