John,
A friend of mine does a lot of spelunking at the dpl and has assembled an awesome web page listing the page numbers of a lot of narrow gauge stuff. There are instructions at the top to get you to the base collection of RR photos and then the page a photo is on of say, D&RGW #463. I have found that the DPL may have added a page ehre and there that throws the numbers off in some areas but they are only off by one page, usually the one after the listed one.
There is a link at the top in the text but on my machines it is white on white for some reason so drag your cursor to the right of the text at the top - first dozen lines. You should see the URL pop up as you pass over it.
Here's John (Piute) Crandall's DPL web site:
[home.att.net]