 After sponsoring the development of the FP45 passenger locomotive, the Santa Fe requested a similar freight locomotive from Electro-Motive.Where the FP45 was an SDP45 wrapped in a full-width cowl carbody, the new F45 was essentially an SD45 given the same treatment.Where the Santa Fe requested a full-width carbody for aesthetics, the Great Northern saw an opportunity to protect crews from the dangers of winter operation in northern climates.