These locomotives represent a fleet of GP7 diesels upgraded by the Santa Fe in the mid-seventies. While the chopped nose and "Topeka Cab" are the most noticeable, many other modifications were made. Upgraded trucks, new electrical equipment, air conditioning, four-stack exhaust manifold and removal of the dynamic brake (if so equipped) are some of the others. As per the prototype, the details of these units differ from road number to road number. Our models represent these differences. Two of the units include the modified dynamic brake system and the other two are engines that were not so equipped. Three represent the "no drop step" option that was standard on Santa Fe early Geeps. The fourth unit has the "always down" drop step common to most of these rebuilds. Side skirts vary from unit to unit as does the horn, antenna and mirrors. All of these details are gleaned from many photos of the prototype. Details that you've come to expect from a Genesis model.