The owner's manual may be available on Airstream.com. Airstream has posted copies of many of the old owner's manuals there.
I replaced the "115v load center", or circuit breaker box on my 66 Trade Wind. I also replaced the 12v
fuse panel. These are two distinct electrical boxes in the trailer.
The circuit breaker box looks similar to the one in your home, only smaller. My old one was about 8" square. It was located in the street side rear wall behind the "medicine cabinet" door. There was a main breaker of 20 amp, and two 15 amp breakers protecting the 115v outlets in the trailer. The shore power cord goes directly to the circuit breaker box.
fuse panel was located in the back storage compartment of my 66 Trade Wind. The purpose of this fuse panel is to protect the trailer from shorts like a seized fan motor. Your 12v
battery or the converter feed this fuse panel.
Sorry, I can't post pictures due to limited bandwidth in this campground. I'll try again when we move to a better WiFi.