69 273 headlights wont turn on

Functionally 1969 works the same way as illustrated before.
The only difference is the junction for the ignition and voltage regulator is located at the regulator instead of the ballast resistor.
upload_2020-7-25_7-54-30.png

When the engine is off, or for any reason the alternator isnt producing power, current will flow from the battery when a circuit is closed.
For example, key off, parking light on.
upload_2020-7-25_8-0-35.png

Furthermore, as long as there is no resistance in the lines, the voltage should be the same in all the wires connected to the battery.
In reality there may be a small drop in voltage at the connections and switches the current is flowing through.
Something like this would not be out of the ordinary.
upload_2020-7-25_8-9-5.png