This is the industrial version of Allis Chalmers D21. With series 1 having 103 HP and series 2 having 127, the Industrial D21 was the most potent D21. The standard model had 93 HP for series 1 and 116 HP for series 2, but the 60th Anniversary edition was enhanced to 103 HP for series 1 and 121 HP for series 2. I reskinned it to the Industrial version after USA Agriculture converted the original, North Woods Farmer reskinned it to the 60th Anniversary version and added a cabbed option. 1963–1965 for series 1 and 1965–1969 for series 2.

Thanks to MrFarmTastic13