By the mid 50s, increasing pressure from long-haul trucks, declining passenger revenues and mounting costs forced western railroads to find new ways to improve service. Faced with expensive overhauls of early cab and hood unit diesels, many began looking at new equipment as well as ways to improve existing motive power. In 1955 Union Pacific equipped several GP9s with turbochargers as an experiment. Their success inspired EMD to create its own turbocharger for the 567 prime mover, leading to the introduction of the six-axle SD24 in 1958. Further experiments in 1959 created a four-axle version, dubbed the GP20. Early in their careers, the new units were typically assigned priority freights that demanded higher speeds. With the arrival of newer power, they were gradually bumped into secondary runs, and eventually spent their last years in local and yard service. Following their retirement, a few went to work for shortline operators.
 
The classic GP20 is a great addition to your roster and features:
 
*Factory-Installed Sound & DCC Sound can be operated with a standard DC power pack as well as DCC controllers. Sound features include: Diesel Engine Sounds, Horn, Bell, Squealing Brakes, Doppler Effect and Air Let Off (in neutral); Trailer mode mutes whistle and bell for double heading.
 
* Prototype Specific Details * Retooled Handrails & Other Parts for More Accurate Detail * Over 135 Factory-Applied Parts * Consumer-Applied Parts Pack Included * Heavy Diecast Chassis * 5-Pole Motor with Skew Wound Armature * Precisely Meshed Worm Gear & Spur Teeth for Silent Running * LED Directional Headlights