The eco-633 was one of the first of ILW’s Cummins-equipped (QSK78 for ~3300 HP) locomotive line. The OSW had ordered them before the 2007 merger, but they did not start rolling off the production line until after the merger was finished.

The first few of the order were built on frames from retired EMD SDP45 locomotives, so were s-t-r-e-t-c-h-e-d out to fit the frame.

Railroads preferred the more powerful eco-642 locomotives, so this model ended up being dropped when ILW’s 4th generation catalog was released.

The OSW units are now all in service on the Great Lakes Central & Michigan Southern railroads.