Well I'm new to all this, but I'm fairly certain. The plate on the inside of the door frame has a spot for both trim and paint. Trim is above paint, and trim is blank. Paint says 234G. There's a chipped place in the paint behind the cab, that shows a darker blue, which is what I've come to understand Mariner Blue would be. Would some painters still have been using that paint in 1956?
Also, would anyone know what color the insides of the trucks would have been? I'm not really finding reference to that, either.