I think that Lionel did a great job on the detail of the Vision Line Challenger and Big Boy. EXCEPT. Why are the marker lights on the tender lit in red? In fact, why are there marker lights at all on any tender? In all the videos I have looked at, I can not find any marker lights that are lit in red while the train is in operation. Maybe if the engine is running without any cars, or as a pusher, they might have turned on red marker lights on the tender.
This also brings up another issue I have, why are classification lights always lit in green? My understanding was that classification lights were clear or white, and were turned on only when special circumstances existed. "Green. Indicated that, while the train displaying the lights was a regularly scheduled one, a second section was following behind it. " White was used only if it was an extra train, not shown in the timetable.
When Lionel, MTH and others advertise a prototype correct engine, I wish they would discontinue marker lights on tender and correct the classification lights. Yes, I know that some roads had marker lights permanently installed on tenders, such as the Penn, but most all others did not use marker lights on tenders except is they were pushers.