1965 AS Overlander International Wiring diagrams from the original manual. If a cable has 2 wires it's usually 12v, 3 wires 110 ac, your main entry cable if it hasn't been updated was aluminum wire which you should changed.
doug - the previous owner removed the univolt from the trailer and also most of the bathroom leaving only the tub - circut breaker box is intact along with the wires leading out of it - there are (3) 110v(house)wires in the rear that are capped including a 12v red/black wire.
would it be possible for you to take a photo of the univolt in your trailer so i can get some idea of the wires that are leading into it??
I restored mine over the last few years and changed out the Univolt and most of the rear wiring. I added a stand up shower and gray tank but keep the rest original. Might be a Univolt only page. There was a small red/black that went up to the battery monitor but most of the 12v was blk/white house wire.