44-Ton Davenport Switcher 1 at Fort, Smith, Arkansas on June 27, 1958 (G.B. Mott).
This photograph is in the book Frisco Power by Louis A. Marre and John Baskin Harper. It starts Chapter 3, Small Units, on Page 27. The caption indicates the units were in storage, but had been moved outside for their monthly inspection and startup.
Also the Frisco Power caption attributes the photograph to Louis A. Marre. The caption above in Frisco Archive attributes the photo to G. B. Mott.
SLSF 1 was acquired in February, 1942 and used as a trade-in to the Electro-Motive Division (EMD) of General Motors in February, 1967. During its Frisco ownership the unit was leased from 1958-1964 to Pullman Standard Car Manufacturing Company at their car building facility in Bessemer, Alabama.
SLSF 2, visible beyond the turntable pit, was acquired in April, 1942. She was the first Frisco diesel to be retired. It was sold to the Tulsa-Sapulpa Union (TSU) Railway on March 30, 1960. On that railroad it became TSU 2.
Special thanks to Mark Davidson.