Re the mysterious UNITED STATES ARMY vehicle in the dark 476 photo: As I recall, the army tested two different diesels at different times, as well as some experimental type of box cars. Unfortunately for identification, the diesels and box cars had very similar profiles. Here is a photo of the first army diesel from John Norwood's "Rio Grande Narrow Gauge" book. My guess (after 60 years) is that it is the diesel, but the box car can't be ruled out. Perhaps more knowledgeable NGDF experts can weigh in.