It use to be a dyno-matic garden tractor.
We used to factory hydrostatic transmission and original rear end. There are break discs on both sides and the steering wheel presses the brake causing all the power to go to the other track.
This action does need a lot of power and having so much truck on the ground creates a lot of resistance.
Kevin E:70 Hp it should pull a 3 bottom plow easily especially with Tracks My Farmall H only has 50 Hp Tops and it yanks a 3 18'' Plow around pretty well in a Clay type ground