there are minor variations over the years, but I think the 55.2 diagram is actually a carry-over from the 55.1 and doesn't show actual production .... the 12ga wire you see from the ammeter to the light switch is actually to a junction on 56 and later diagrams, that leads back to the regulator and is intended for the accessory fuse panel supply
there should be a 14ga red wire from the pass side of the ammeter to the ign sw BATT terminal and a 14ga red from that ign sw BATT terminal to the light switch BAT terminal .... and try to think of the connections in terms of current flow, the ammeter simply passes current from the generator/regulator to the battery, so connections are from the regulator and to the battery, when the engine is running things get power from the generator, when it's off they get power from the battery
the colors on the diagram indicate which wires go where, and the items on the diagram are in the exact orientation and position that they are on the truck, with a line across the diagram labeled 'front of dash' [which means firewall in factory-speak], so that all you need to do is put the right colors on the right terminal - the right terminals being shown in the expanded views
if the regulator is clicking [indicating current flow] at odd times, something is hooked up wrong or it or the generator may be bad - or you didn't polarize it?
Bill
