Morse Brothers was also a used railroad equipment dealer and had a large yard full of old equipment in Denver into the 1940's. They also did scrap entire railroads, the Colorado & Northwestern / Denver Boulder & Western being one example. Morse Bros. sold all of the C&N-W's rolling stock and locomotives in 1920.
The "cook car" in Salida does appear to be a modified boxcar. It is larger than the D&RGW 3000 series boxcar it is next to, so it is most likely not a D&RGW narrow gauge car (the 3000 series were the largest narrow gauge boxcars the D&RGW had) So, it would appear that the car is either an ancient standard gauge car, or possibly a narrow gauge car from another railroad.
The Morse Bros. connection does leave open the exceedingly slim possibility that the car is a former C&N-W car. The C&N-W boxcars were taller than the D&RGW 3000 series cars and Morse. Bros. once owned all of the C&N's cars so there is some slight circumstantial evidence.
More photos and information (measurements etc) of the car will be needed, but it looks to be an interesting mystery to pursue if it is at all possible
Jason Midyette
for what it is worth, car 0470 mentioned in a post above is a passenger car.