This isn't comparing apples with apples at all, those -36's have to be rebuilt, obviously keep going or die and taking both RR's along with them.
It's not like Baldwin or the Rio Grande, both deceased, had built or are still in business building more modern steamers to which the management of both the D&S and C&TS can draw from thus allowing their precious aging relics to be put out to pasture or turned in to Rebar.
And Dale, re your comments on the C&S #9 having the bell jacked up, well the C&S did the very same thing, new Boiler and Cylinders in 1900 and a new Frame in 1917. The #9 was from 1884 remember. If the management hadn't been so tight #9 would have been scrap a long time ago.