Wow... that's some list... I think you could probably even delve further, and breakdown each of the roads to that many (I recall an Erie Lackawanna article on its predecessors that I read recently had something like 100 roads that formed the Erie and 100 roads that formed the Lackawanna).

That being said, Ann Arbor, Pennsylvania Reading Seashore Line, Niagara Junction, and then later Raritan River, come to mind as companies whose locomotives I saw.

I feel like the Buffalo Creek Alco switchers were in the Conrail deadlines as early as 1978. Maybe as a subsidiary, they used CR power after that?