One of the best investments I made for modeling D&RGW narrow gauge passenger equipment was the pair of Colorado Rail Annuals on the subject. No, 24 covers the passenger train operations; No. 25 is the car by car treatment of the fleet. According to that source, car (2nd) 212 was rebuilt as combine 215 in 1887. In 1928 No. 215 was rebuilt with a cupola, roof walks and ladders for use on the Pagosa Springs train. June, 1936 - car 215 painted red. 1941 - cupola removed, but roof walks and handrails left, car re-numbered 212. Repainted Pullman Green in November or December.
This does not directly answer your question. While anything is possible, I would guess the car got repainted at the conclusion of the work to remove the cupola and its renumbering. Repainting the car red for a period of at most a few months, does not seem likely. Still, it is possible. My guess would go with green after the cupola removal, until painted for movie work and then for the Silverton train.
Charlie Mutschler
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