High Quality Content by WIKIPEDIA articles! The NRE 3GS21B is a low-emissions diesel road switcher locomotive built by National Railway Equipment. It is powered by three Cummins QSK19C I6 engines with each one developing 700 horsepower (522 kW) and creating a total power output of 2,100 horsepower (1,570 kW). At least 16 3GS21C genset locomotives have been produced to date at NREC`s Mount Vernon shops in Southern Illinois.