Just bought a bunch of Marx junk engines to restore, and in the pile were two sets of E-7 side frames made of metal! In my years of collecting and repairing Marx trains, all E-7 side frames I've come across have been made of plastic. Are there any Marx historians out there who know anything about these? I'm guessing these were used on some very early models, and being the penny pincher that Louis Marx was, found that plastic was cheaper to produce. The metal ones also have openings where the plastic ones do not. (see attached) Can someone shed some light on this phenomenon?
