Hi and welcome from Colorado. Holy Cow, Kemosabe ! I hope you weren't hurt when this thing fell in your lap.
It appears it is the shell of one the 10 or so
1962 Western Pacific Railway foreman houses used way back when. Here is a link to Timeless Travel of Wheat Ridge, Colorado, who rebuilt one of these into a beautiful rig.
But maybe I'm all wrong on this.
Your thread doesn't due justice to your find. There will be a lot of us Airstreamers interested in seeing this relic and trying to identify what it is.
David
http://www.timelesstraveltrailers.com/mid-century