Only four railroads owned the 2-6-6-4 simple articulated type. The Pittsburgh & West Virginia introduced it in 1934, followed by the Seaboard Air Line in 1935; its locomotives were later acquired by the Baltimore & Ohio. (This list does not count the Southern Pacific's 4-6-6-2 cab-forward articulateds, which might be considered 2-6-6-4s in reverse, but these were essentially 2-6-6-2s with the truck under the cab enlarged to four wheels as a pilot truck.) It was the Norfolk & Western, however, which brought the 2-6-6-4 to its peak of development, constructing 43 locomotives in its own Roanoke shops between 1936 and 1950. For the specifications of the N&W's class A series, consult the commentary for No. 1238.
No. 1218 survives and was a partner of class J 4-8-4 No. 611 in the Norfolk Southern's steam program. My brother, David Leonard, captured her on film in this service at Coyner Springs, Virginia on April 26, 1987. When the NS steam program ended suddenly in 1994, No. 1218 was undergoing a rebuild which was suspended, and the locomotive (with, presumably, its disassembled parts) was returned to the Virginia Museum of Transportation where it is now displayed.