If you have an internal resisted 12 volt coil, then no ballast resistor is needed. If you have a 6 volt coil or, a 12 volt external resisted coil then you need the ballast resistor. Hum.... looks like the factory had some 6 volt coils left over...for some years, and years. Then they went to an internal resistor....the spec for the coil itself did not change much it would seem. Actually that is good use of engineering resources, The original coil was well thought out and no big changes were needed. The real issue is the current at the points. That is what stayed the same.
The connections are to serve the following functions, 1, Ammeter is in the charge circuit. 2 Coil should go through the switch, 3 Headlights and dash lights are on the charge circuit. Gas gauge, radio if you have one are on the switch. Early trucks only needed two connectors. 1, Battery, and 2, every thing else. Starter was hooked to a floor switch and that went to the battery. Newer trucks have a spring loaded position to engage the starter solenoid. Newer still the Acc position was added. 54 would have been in the early group I think.
