The NRE 1GS7B is a low-emissions diesel switcher locomotive built by National Railway Equipment. It is powered by a single Cummins QSK19C I6 engine which develops a total power output of 700 horsepower (522 kW). There have been nine 1GS7B locomotives produced to date, manufactured at NREC's Mount Vernon shops in Southern Illinois, and at NREC's Dixmoor shops. It's also the only current single-engine switcher marketed in NRE's N-ViroMotive catalog.