In 1989, the Green Bay and Western bought out the Lake Superior and Ishpeming's fleet of six RSD-15s as well as the railroad's entire stock of Alco parts and tools (the Alco RS-27 was the four-axle equivalent of the RSD-15 and shared many parts).  These engines were the only six-axle diesels ever owned by the Green Bay Route.

It is a common belief that the GB&W intended to cannibalize these locos for parts to keep their own fleet of Alco locomotives going strong - but the G B W repaint on the sides of the long hood of the RSD-15s makes a person believe that at least some of the six engines were destined for revenue service.  Rumors have them operating east to Kewaunee, but there doesn't seem to be any photo evidence of them going any further than the Wisconsin Central interchange at McDonald Yard, a few miles north of Norwood Yard, while on the GB&W..

The engines soon wound up with sister railroad Fox Valley & Western instead as as extra power for Green Bay to Milwaukee trains.  A few trips proved that the locomotives were unreliable in regular service and they soon went to the Wisconsin Central's North Green Bay roundhouse (former C&NW) where they were scrapped in the mid-1990s.