Earl,
That danged white scheme with the green trim is pretty hard to nail down.
It's like the elusive chimney/no chimney question. Many bad dates in captions.
Dorman's Durango book shows a picture of the white depot dated, he says, in 1953. Two pages later, there it is, white again only this time he says it's late 40's early 50's, no chimneys, San Juan equipment in front.
I've never been satisfied with any dates I've seen of the white depot, but every picture I've seen of the last run of the San Juan in 1951, the depot was buff/brown, with chimneys. I can't believe it was white more than once and it was definitely white for a while sometime before 1951 and definitely Buff afterward.
Aliens again, no doubt. Interplanetary Aliens. Interplanetary Aliens studying Chimneys.