The EMD SDP40F was Amtrak's first, official, built to order locomotive (previously they had operated using second hand equipment, such as E8's, F7's and even GG1's). A need for new and more reliable equipment spurred the development of the SDP40F. Based on the framework of the SD40-2, the SDP40F was geared for speed, with a top operational velocity of 100 mph and a pair of steam generators to supply heat and hot water for the passenger trains it would pull, such as the ex-Santa Fe "El Capitan" and "Super chief" (renamed the "Southwest Chief" in its combined state).

Thanks to their SD40-2 heritage, the SDP40F's were fairly simply converted to freight use, which allowed them to maintain relevance after the introduction of their successor, the EMD F40PH, in the late 70's and early 80's. A number of SDP40F's were traded over to the Santa Fe Railway in 1984 where they were modified and repainted into the distinctive warbonnet scheme and maintained in service for nearly 15 years.

• Type I Car body details represent the prototypical appearance of these units "as built" - No front porch railings, Steam Generators, Nose headlights, and forward mounted 4-Chime air horns.

• Type IV Car body details represent the prototypical appearance of these units in later freight service - Front porch railings, notched nose, Nose/Cab headlights as appropriate, additional roof antennas, Cab A/C units as appropriate, and rear mounted 3-Chime air horns.

• Amtrak Phase I and Phase II paint locos are a perfect match for the Amtrak El Capitan 10-Car Set, Amtrak Southwest Limited 8-Car Set or Phase I Amfleet I Cars.

• Freight Versions can be operated with Kato's intermodal equipment, with the BNSF Maersk unit being a perfect companion for the Maersk MAXI-I.

• All locomotives will be equipped with body mounted KATO magnetic knuckle couplers

• Locomotives feature directional Golden White LED headlights and illuminated preprinted numberboards

• Locomotives have a powerful five pole motor with all wheel electrical pickup and blackened wheels

• Locomotives are DCC friendly