A little bit of useful info. My 4905 has the 24 volt headlamps. 12 volt were an option btw. It has that same connector, but instead of connecting to the resistor block, it has a socket plugged into that connector with 4 short loops of wire. Wire loops connected as follows: D to J, C to H, B to G, A to F. Terminal E is blank or not used at both male and female connector. It is a connector installed by GM when coach was built.In case you decide to change to 24 volt headlamps later.Even though mine doesn't have the resistor panel, the mounting holes are there. I was going to install the resistor pack from the other coach, but am going to go with leds instead. Plus, someone cut the plug off the panel and coach headlight harness and jumpered a piece of trailer wiring harness with but connectors.
Sorry, don't have a spare. I'd call Luke. It would be easy to unplug the jumper female end off one of his parts coaches.
If it was mine, then I'd change over to the 56 with two plugs. Probe wires with a test light. Driver's side in one plug and passenger side in other, or high beams in one side and low beams in other. Easier for diagnostics down the road. What ever.