I'm pretty sure that Marty is on the right track. I have a print of "Waterstop at Hancock" where Otto Kuhler painted a South Park Mason Bogie with a butterfly snowplow. There was quite a bit of controversy about this as this type of plow wasn't utilized until the C&S days. I came across a photo that Otto probably used as his template and, in it, a 2-8-0 has a plow with the Mason Bogie in the rear and the plow was a much simpler and smaller design. It would indeed seem that Mr. Kuhler was not adverse to changing details to make the picture more visually exciting!