I have the same (almost) set except for the dump car and its from 1940-41 as best I have been able to research. I also have an engine but its a 2-4-2 and smaller than the one in Peter's entry above and also is a shelf queen. The cars would look a little "small" when run with Lionel scale or other O scale trains because they were made at 3/16" scale but O-gauge as opposed to 1/4" O scale. I also agree pulling them with a Marx loco and scale cars which also approximated 3/16 " scale, when you can determine the scale at all, and the listed ones 999/666 are great runners but don't forget the 333 or 1869 . Yes you have to create a "transition" car to alter the couplers but a common Marx flat car and a little work will do this. Note- candidly when in a hurry I have taken care of this with a "band aid" of a little wire wrapped around the coupler from the tender to the first car sort of tying them together (yes I agree its crude but it does work).
Don
