Hey, Crayuft,
As indicated in my earlier post, #478 appears in a Beebee & Clegg book with it's new diamond stack. Since it's a different stack than the one on 476, and since the book was published in '58, I'm convinced.
John West's 1961 picture of 473 in Durango shows the engine with full footboard steps, and no fake stack.
Since we've determined that there was no second train until 1964, it's clear that the D&RGW was set on the "image" early as Rio Grandeland's "Trip to Yesterday" took hold, even with a single train.