Earl Knoob has good info about the loco's he discusses. One must look
carefully at the pictures, though.
This is all from memory but IIRC, several pictures of K-27's on the South
side of the RGS had swapped tenders, almost impossible to verify which
because the tender numbers weren't visible. In particular, 452 or 461 are
shown in several photos in volume 9 or 10 of the RGS Story trailing a
doghouse or windbreak on the tender around 1947, unlike the "matched"
version--hauling freight between Dolores and Durango. And very late in RGS'
game, 455 used 452's tender on a few runs. C class tenders were frequently
swapped as maintenance and wear sent the originals to the RIP track.
I can't recall why this was so important to me at the time but I was a more
uptight rivet counter back then. After starting my current layout, reason
prevailed because it's nearly impossible to fit every favorite variation of
any RGS item to a precise date because photographers weren't working every
day--or even every week. So on my layout, all the days depicted are days
when the famous, published photographers were not around. Solves lots of
problems and recognizes the ability of RGS employees to innovate and adapt
on a daily basis.