I have no knowledge of 1964
I have a 1968
24' Tradewind Landyacht, that has two pull out sofas and they were called "goucho's". I would bet that they are simular in design and function.
The goucho's in my Airstream were located: one in the front of ther trailer over the fresh water tank, with three storage compartments under. The other was located on the street side of the trailer, over the mid-section, with three storage sections under.
The goucho's were constructed of oak framing. To expand the goucho you lifted up on the outside edge of the bed and pulled outward. The gouch expands fron a single wide bed to a double wide bed.
I could go into more detail but this gives you sufficient information to research the airforms archives and to pull up diagrams, designs, and complete with replacement parts manufactures contact information.
If you need more help, just p-message me. Like everyone here at this site, we will do everything we can to get you the help you need to make your Airstream 100 % functional.