Russ,
From what I understand the major rebuilds and major servicing was done at Alamosa--does this mean that Salida couldn't do the work? No. I was speculating that the use of the 490 west of Alamosa was because it was a break in type run after servicing, but it could have just been due to a power shortage and it was available to make the run. I don't know if Salida or Alamosa did the work on the 492 after it had it's roll over near Mears Jct--if you've ever seen pics of it after that it's surprising it still exists today. Just as an example I know when the 37's were built they were shipped to Alamosa for the final completion of the build. I think the shops in Alamosa were more extensive than that of Salida.
William
aka drgwk37