Voltage Regulator problem

Might be worth checking the VIN. Diagram shows a wire for throttle solenoid for 340s that connects there. Not that the shop manul is always 100% accurate, but worth checking.
View attachment 1715768677

CE 2(N) is the wire coming out of cavity N in the firewall connector.
It goes to a welded splice that's in the wrap.
From that branches out
one wire to the ignition J2A
a wire to the regulator J2B (that senses voltage)
a wire to a connector, that then joins two braches - one to the choke assist and one to the alternator rotor.

Originally there was a multi-cavity connector near the back of the engine. Check for the the green field in that, if its still there. Probably was on top of or along side the valve cover.
View attachment 1715768682

I ran the VIN and it's just a 73 with a /6