There are a lot of 3rd division unpublished photos. Not as many as I would like, but many.
I have never understood why there are so many RGS photos, but so few of other lines. I think every blade of grass along the RGS has been photographed. Not that I would want to take even one of these away, just find it hard to understand why so few on some of the other lines (like Crested Butte, Baldwin, Lake City, etc.). Many of my 3rd division photos were made by D&RGW crew and are not professional quality in most cases.
I think the pro photographers were trying to photograph as much as they could and photographed what they thought was most likely to go. I was told by a couple of them that they actually thought that the Crested Butte branch and Marshall Pass would last longer than Silverton and Cumbres (because of the Crested Butte coal). There was plenty of coal there when the D&RGW shut it down. Was just cheaper to get it from the Trinidad area (no transfer from narrow to standard gauge).
Longest narrow gauge train ever operated on the D&RGW (and probably longest anywhere in the US) was 125 cars from Sargents to Gunnison in 43, but no photos as far as I have been able to find.