How does UP number its locomotives?
UP4
Ahhhh' by using numbers :D!!
http://utahrails.net/all-time/all-time-index.php
This is for diesels, dates back to 1934. I have their steam roster somewhere, will try to find if you need it also.
I'm always delighted to meet another UP modeler, approximately where are you located? I'm in Colorado, near Craig. For two years have felt like "The Lone Modeler", no one else around here into trains, just football, skiing, hunting and "yeehaw".