The Michigan Southern Railroad was created in 1989 to operate an segment of the Lake Shore mainline across southern Michigan (Sturgis to White Pigeon), but only operated as an independent railroad for about 8 years before the Illinois & Michigan purchased it as part of their attempt to build a viable railroad from Detroit to Chicago.
It had started up with a small pile of Alco power, but after the takeover all of those units were replaced with GP-38s (most of the Alcos were subsequently scrapped, but RS-2 #466 went to the Great Lakes Central for an unsuccessful tourist train, and then after 9 years of sitting dead on a siding ended up being sent to ILW to be rebuilt into a RS-250), which were used until the I&M was merged into the Parsons Vale system.