Chile Line boxcar

In looking through Richard Dorman's book on the Chile Line today, I noticed that in many photos taken around 1939-1941, the Santa Fe mixed train has a Rio Grande 3000 series boxcar right behind the locmotive. The car is faded and has only a number visable (no Rio Grande Herald, D&RGW etc) It looks to be the same car in many of the photos, and is sometimes the only freight car in the train. This car was on the last train, September 1, 1941, right behind locomotive #470. (for those who have Dorman's book, there is a photo on page 30 that shows this) Of course none of the photos in the book are clear enough to make out the car's number.
I would assume that lots of less than car load freight was carried on the Chile line. Did the D&RGW assign a car to the run for this purpose? (Passenger equipment seemed to stay captve ion the Chile Line, so it would not be out of the realm of possibility for a freight car or two to be similarly assigned) That would explain this car showing up so much. Also, does anyone know the car number or have a clear shot that might show the car number. It would be interesting to know if the car still exists.
Jason Midyette