2' and Gilpin Fans- a new caboose?

I just won a bid on a eBay photo described "Old Train and men" which was a 3/4 view of Shay G#4T backing a 3 car train-2 flats with ore sacks covered with miners. But the interesting end car was an old excursion car with the side canvases. The never published view of the car has end walls and a large window, half the width of the car, containing 6 panes of glass, AND a smoke stack!
This looks like it had the number on the side of G-600-T. This would serve well as a caboose as it had plenty of heated room for crew and riders.
I will offer the photo to Dell McCoy, "Sundance Publication Ltd." to be used in the next book on the Gilpin, which he has in mind. Anyone else have a view of car #600? I could be wrong on the number but no question the car was rebuilt with two end walls added. The photo is fantastic on original hard cardboard.