I found this photograph at my link page Fallen Flags.Org, located to the right of your computer screen at www.rr-fallenflags.org
I grew up on the near southwest side of Chicago during the 1970's, and I fondly remember seeing these rebuilt 1950's era Atchison, Topeka & Santa Fe Railroad EMD yard switchers working the north and south humps at Corwith Yard, operating multiple unit with as many as 4 of these on transfer trains, or operating solo on the Santa Fe's own industrial I.N / Illinois Northern branchline local Monday thru Friday in my old neighborhood northeast of Corwith Yard.
Railfan photographer Dennis Schmidt photographed Santa Fe S S B 1200 # 1226, at the Santa Fe Corwith Yard in Chicago, on August 27th, 1978.
S S B 1200, was the "New" model number that the Santa Fe gave to these 1950's era EMD SW 7 yard switchers, after rebuilding at the Santa Fe's own San Bernadino California railroad shops during the 1970's. S S B translates to "Switcher, San Bernadino, with a 1200 horsepower prime mover."
The Santa Fe retired these engines from service in early 1983, and sold the remaining ones to Amtrak.