Brian:
The Potash No 3 is pretty much a carbon copy of the c-21 isn't it? Seems to me that Baldwin used that "pattern" for a lot of the early outside frame engines. Weren't the C-21's built before 1900 though and therefore not quite as modern?
I know everyone always wants to find a C-21 to renovate so we would have them alive again. Seems to me that the Hawaii railroad also had a couple of the same type as well as some of the central and south american railroads. The georgtown engines before they got piston valves were close.
Frank
Frank