Condensation in the form of steam also exits the slots when not underway.
What is the story about this engine? How original is it?
Thats the million dollar question?
As far as I can tell or find while cleaning it up everything is original on the truck, It does have a rebuild tag on the carb but no indication of work being done on the engine. When I had the inspection done on it to register the mechanic said they were original plugs, points and wires. The brake shoes are all original with very minimal wear on the drums.