By the early 1970s, many first generation diesels were reaching the end of their service lives. The most common replacement locomotive became the GP38-2. EMD began production of the 16-cylinder, non-turbocharged, 2000 horsepower engine in 1972. Unlike the GP38's engine which drove a generator to supply power to the traction motors, the GP38-2s prime mover drove an alternator which produced AC electrical current that was rectified to DC to power the four traction motors. Another major change for the GP38-2 was the introduction of the "dash 2" modular electrical cabinet. For the past 40 years, the GP38-2 has worked main line freights, locals, switching jobs, yard service, helpers, snow fighting trains, and hump power. Many remain service today.