The RS-1 was introduced by ALCO in March of 1941 with the delivery of the first of two units to the Rock Island. Combining the accessibility of a switching locomotive and the higher-speed tracking of a road unit, the RS-1 started a revolution in locomotive design that was soon embraced by all of the major diesel-electric builders. Now, the RS-1 has been redesigned with added detail including separately applied wire grab irons and coupler cut levers, improved radiator detail and revised roof detail. Other features include a realistic diecast underframe, five-pole skew-wound motor with dual flywheels, directional lighting and AccuMate knuckle couplers. Friction- or roller-bearing truck sideframes are included as appropriate for each roadname.