Gene,

There is nothing in my library that records an F class built with a plow. My records do not go back further than 1919, so it may be, although I don't think it happened.
What may be the case is a car bought, or appropriated from the PRR, and rebuilt with a plow assembly in Iowa. My reasoning is that all of the old pix I have studied show a "V" type, high curved top plow attached to the pilot of a 4-4-0, or a 4-6-0.
Others are more well versed in MW equip. than I, so there might be a slim chance someone can provide proof positive.
My money is on not likely.

Fred Freitas