Bruce Pryor also has a pdf version of the entire letter also available on his website. It is much more complete and illuminating.
[narrowmind.railfan.net]
In 1946 the White Pass felt that the USA 190s were too light for its operation when compared to the 70 and 80 class locomotives and the 66 and 69. But there were delays in getting the new 72 and 73 from Baldwin. The 69 was unavailable during the winter because its cylinders fouled the snow cuts made by the rotaries.
So the White Pass was willing to purchase two of the 190s from the army as an interim solution. The White Pass was also buying two additional 190 class tenders for use behind the rotaries.
Brian Norden