Hey John,
I've run into things of this nature before. Probably, special order, or dealer refit. It is possible that someone could have ordered just about anything. They were doing lots of things to stay open in those days. My referance is the parts list, crossreferanced to the production schedule of Charles City. It does at times conflict, but generally gives a good handle on the normal production. This is how I learned of the 2-3 plow tractor, I then spent quite some time researching this, quite an interesting story, the first ones were built in South Bend, I believe mine could be next to the last one of these. I would be interested in looking over a 2-3 plow tractor built after SN 800018, if it is original, there could have been some interesting changes that were made. I know after SN 800075 there were changes, the fuel tank and fenders are different from mine.
Have a great day!!!
Andy