Reference to CM caboose plans and some photos would lead me to believe that this caboose is one of the 28' cabooses purchased from St.Charles Car Co, between 1887 and 1890 which were CM 415-423. The door, window placement and length are correct. All other CM cabooses were 30' long and had two windows on each side, rather than one.. In addition, a photograph exists of #418 having been rebuilt with an identical cupola to the GC&WR #01. Whether this cupola rebuild was done to the entire series or just #418, I do not know, but this caboose is at least one of those 9 cars.