These 628's were used on the Huron Line out of Winona Mn in the early 1980's. Huron, with its 17-stall roundhouse, was used as a maintenance base for surviving ALCO power on the C&NW.
I was living in Winona at the time, and working in St. Charles. These units were very impressive on account of their size. The design of their carbody, with the cab moved close to the end of the frame, coupled with a high short hood, made them look huge. Much bigger-looking than an SD-45 of similar size.
The C&NW engine terminal at Winona was a regular zoo of ALCOs. C420's, RS-32's (ex-SP, some in red and gray, some in Chrome Crankshart red), smaller RS and RSD units, RS slugs.
I think the idea was to concentrate the minority builders' units geographically to rationalize the stocking of repair parts. I know the Milwaukee Road did this for that reason (FM's concentrated east of LaCrosse; Baldwins concentrated between LaCrosse and St. Paul; ALCOs based out of LaCrosse).