The first group of the Central's K-5b Pacifics, represented here by No. 4907 (originally CCC&StL 6507), came from American Locomotive Company in 1926. They had 79-inch drivers, cylinder dimensions of 25x28 inches, and a boiler pressure of 205 p.s.i. They weighed 297,500 pounds and produced 37,650 pounds of tractive effort, augmented by a booster putting out 9,700 pounds of tractive force. For other dimensions, consult the commentary for No. 4933 following.

This image of Pacific No. 4907 was provided from the David Loeffler collection. The engine is apparently being towed backward from the passenger terminal to the roundhouse by Hudson No. 5395 (note the Walschaerts valve gear in reverse position and the flagman on the pilot protecting the rear of the movement). The probable location is Cincinnati, where New York Central (specifically, Big Four) locomotives could end their runs at a major terminal having arrived from two different directions. The date has to be the late 1930s, after No. 4907 assumed that number in 1936 but before the introduction of the Central's Gothic lettering in 1940. To further pin down the date, No. 4907's flat font end suggests that her smokebox has received the "Selkirk" nozzle-and-stack modifications for improved gas flow through the boiler tubes; this change was applied to many NYC locomotives after being worked out in the design of the J-3a Hudsons of 1937. The photographer remains anonymous.