I recently got the two-book "Steam Locomotives of the New York Central System" set, I'll check the Michigan Central section out when I get a chance. Seems to me when flipping thru the book that the MC Hudsons did have striping when rec'd in the 20's, with the "New York Central Lines" lettering and the small "M.C.R.R.". That striping generally was removed by the early '30's.
Here's a link to a pic of an M.C. Hudson in the mid-1930's...
Not long after this, it would have been changed to "NEW YORK CENTRAL SYSTEM" but still have the "M.C.R.R." lettering.