She was NP 1762, a class W-3 and was sold to the SP&S in September of 1944, according to
Classic Steam Era by Schrenk & Frey. Here's a photo I got from the late Frank Jessup, of Portland Oregon. It's an instamatic photo, likely taken in the early 60s at the Vancouver Park.
This is the only surviving example of the mainstay locomotive of the Northern Pacific. My father worked on many of these W-3 class Mikes, right up until the end of steam in the Tacoma area.