Hello Mr. Van Horn, it's good to make your acquaintance. The "Laramie Plains Line" is a specialty with me because my family had early pioneer experience in North Park, and then my step-grandfather operated a pile driver for Union Pacific and worked on a number of bridges in the 1950's, specifically at Albany and then also worked on a bridge over the Illinois River near Cowdrey.
To answer your question specifically, there is one identifiable piece of equipment that comes to mind immediately, the steam rotary snow plow at the Forney Transportation Museum in Denver was used on the LNP&W.
There are two references you might want to check out, one is "Railroads of Northern Colorado" authored by Ken Jessen in about 1983; I think the publisher is Pruett Publishing and I'm sure it's out of print but occasionally copies come up on Ebay. The other reference is "North Park" compiled by Hazel Gresham, a native of Walden. I think it's in it's sixth or seventh printing.
That being said, Ken Jessen also did a video on the Laramie Plains Line sometime in the 1980's and mentions your family by name in that video. I don't know where my copy is at this moment; I've moved recently and much of my material is packed away. However, you might find a copy on Ebay or some other railroad source.
I have a number of pictures of the line, including some taken in about 1987 just before UP sold the line to the Utah concern that eventually abandoned it. I will give you my contact information below and we can discuss further by email if you like.
Best regards,
Jim Burrill
Ft. Collins, Colorado
844jim@gmail.com