13 hours ago, Jan van Eck said: Great stuff! Note that 4014 seems to be oil-fired; my guess is that the original configuration was for using Bunker "C", probably 180 centistoke material. I would be surprised if the Union Pacific can even source that oil today; those run-bys are more likely to be fuelled by rail diesel oil. the Big Boys were originally intended to pull full consists up the grade over the Wasatch Mountains, without having to stop to couple on any helper locomotives. But I think they ended up in passenger service for a decade, then relegated to hauls "on the flat" instead of those heavy grades. I am not a rail aficionado, so my memory is a bit hazy on that.