Anthony, if you can scan the wiring diagram in higher resolution as a PDF, I'd love a copy for my records. Any original documents are rare.
As for the '69 wiring, I think it's the same as my '69 Overlander. The pictures look the same. This is what I have traced out on mine:
The RV plug and cord at the back of the trailer goes directly to the Main 30 amp breaker box in the bathroom closet above the water heater.
From there, the 120 vac circuit runs in a white Romex around the rear of the trailer, past the fuse block in the rear, past the blue converter (Univolt) on the side cargo hatch, up inside the wall, along with the bundle of wires (from the fuse block in the back cargo area), all the way up front to the Secondary breaker panel at the Command Center. The
Secondary breaker panel in the front has several breakers. One breaker feeds the 110 vac outlets inside the trailer. One breaker feeds back to the Univolt. There may be another breaker feeding the outlet behind the Command Center.
If "nothing" works, the main 30 amp panel would be the place to check. You might have a bad RV plug, or bad breaker. If that's good, check the front breaker panel, and see if the 110 vac is there. Then follow the branch circuits from there.
If the Univolt is "humming", it has 110 vac. You can test at the fuse block assembly in the rear cargo hatch, to see if there is 12 volts DC back there.
The 12 volt
wiring is a little strange, because the 12 volts runs from the Univolt, back to the 12 volt fuse block, across several connections, and then out to the Command Center, then out to the cabin lights and other stuff. A couple wires run from the resistor plate to the Amp gauge at the Command Cenetr, too. I can dig up the wiring detail, if needed.
Also, the Univolt WILL provide 12 volts to the cabin lights, etc, without having a battery connected.
Replacing the Univolt with an electronic charging system is much better on the batteries, and is cleaner power, but you don't HAVE to replace it right away.
I reconfigured my wiring for heavy duty use. I didn't like the 120 volts running all the way to the front, and then back to the Univolt. (I'm using (2) inverters and (2) batteries for 4,000 watts of battery power.)
I removed the Main 30 amp panel (which is actually a 60 amp load center) entirely, re-routed the RV plug to where the Univolt is, and installed the 4 circuit breaker panel on the bathroom wall below the bed. (I removed it from the front Command Center, and connected the cabin outlets and Command Center together onto a single 20 amp circuit.
I installed 4 breakers in the new breaker box, and connected them to; the Univolt (now electronic unit for 12VDC and battery charging), the cabin outlets and Command Center, another circuit for a 120 volt water heater, and the last circuit is dedicated to a set of outlets feeding heat tape that is distributed all along the new PEX plumbing.
I also connected the switched circuit that feeds the Marine water pump, to the new propane water heater, so it only operates when the water pump is ON.
Hope that helps shed some light on the wiring.