Warren,
The tank on my '60 was held in place by two or three straps which were
screwed into the floor. Simple stuff really. You will also need to remove
the mounting stuff at the filler tube from outside the trailer, remove the
drain cap (underneath) and water line feeding the trailer.
The air pump to pressurize the tank would of been an option in the 50's.
Your trailer might not of come with one.
I would not even bother inspecting the wires located within the body
cavities of the trailer until you have inspected the light bases, bulbs,
plug/wire connections, and grounding. Apart from rodents the wiring is well
protected where all these other areas are not, or are known to go bad.
Scott