The first ten M-64s were actually ordered from Alco, patterned after the Delaware, Lackawanna & Western's 4-8-4s and including Alco's newly-offered single-piece cylinder and frame casting. However, Alco was overbooked with orders at the time, so they subcontracted construction to Baldwin. The D&RGW was not pleased, and consequently Alco purchased the engines and leased them back to the D&RGW, with the terms that they could be returned in five years if the railroad was not happy. Also as a part of this deal, the final four (1710-1713) were acquired under the same terms. Clearly the railroad grew to like them, as they kept them through the end of steam. (From Robert Schaefer's "D&RGW 4-8-4 Westerns" in "The Prospector", Volume 2 Number 2.)
