OK, here goes. I got a model of a G scale big boy boiler engineering sample here. It occurred to me that it looked just like the Challenger's boiler. I started thinking it was mislabeled? I'm online looking at pics and I hate to say this. I can't tell the difference? Sure the bigboy looks bigger from the sides of the whole loco. From the top view the boiler's look the same to me. What am I missing?
( I think there's a number 69777 on the alco buider's plate Schenectady works may 1942
also a superheater throttle patent #)