I really like the Atlas Trainman GP-15-1 offering. It's a nice runner of a prototype I'm a bit surprised is available to us in this scale.
Anyway, here are some final shots of my unit, after fading w/ an airbrush slightly overall, brush applying acrylic faded yellow to match proto photos, although of 1622 as Atlas managed to choose a UP unit with no proto photos available online that I could find.
I redid the faded areas of the gray after rechecking my photos and noticing my initial mix of color was far too light after drying. A wet Q tip removed all the faded areas easily, so I could reapply the new shade. I then blended these in with some light dry brushing and stippling around their edges, as they are less sharp in real life than the faded yellow areas.
I hit the trucks with various washes to dirty them up and provide a well used look. The fuel tank was faded similarly to the roof, but I added fuel spills and some rust areas by dry brushing a lighter oil rust shade over an acrylic base rust shade. I didn't have roof photos to use, but noticed in a couple side shots that one angled cab roof side was notably rustier than the other, so that received multiple layers of washes and hand painted streaks then blended together with a dry brush with a touch of alcohol on it.
Finally I dirtied up the plow and rear pilot, and painted the safety white handrails by hand. She will get an all weather window once I can locate a suitable part.