It’s been several years since Union Pacific F-units have appeared in Denver. But suddenly in the fall of 1968 a group of F9’s transferred from the road’s Northwestern District have started showing up on Kansas and Nebraska lines, which accounts for the presence of F9A 524 at UP‘s Pullman engine terminal the morning of September 22. The engine and a companion SDP35 have come in overnight on a Kansas City freight. There is some controversy over what to call the 500-class F9’s, all 83 of them remanufactured in 1958 at EMD’s La Grange plant from F3A- and B-units. Only the original truck frames and carbodies remain. The diesel engines and electrical equipment are brand new. Railfans refer to them as F9Am’s; to UP and EMD they are simply F9As. Note the cab handrails extending all the way to the roof, a feature unique to these units. In three years, along with 30 other F9’s, the 524 will end up on Rock Island as that road’s 4159.