EMD F7A unit No. 813A anchors a three-unit lashup in the service area in this photo taken in March 1957. While two- or three-unit combinations were common on main line freights, I don't recall seeing a four-unit combination of EMD F units, though I may have seen three F units trailed by one of the Alco road switchers. The GM&O's route through Illinois prairie country did not have the heavy grades that might have made longer lashups common.