Photograph was taken at Lindenwood Yard. The locomotives are parked south of and adjacent to the diesel shop. They are west of the service tracks fuel and sand facilities.
The date must be August 1968. By 1988 the F units and U25B units were all retired. The photograph could not have been taken post merger.
#810 is an early version of a U25 B. Notice the one piece windshield, the handrail stanchions are mounted on the walkway rather than the side. Early versions had brake wheels, although, I have seen photos with brake handles.