I had a gravely 2whl tractor with a couple to splined shaft. A friend sold me a 40:1 gear reduction box (a heavy unit from a freight elevator, I think). I mounted that to the front, with the shaft pointing straight up. Onto the shaft I mounted a round steel plate and a 2in dia pience of water pipe 6in long wrapped with duct tape.
I then bought some 1in poly rope. Instead of a winch, this thing worked like a sailor's capstain. Anchor the tractor, start the PTO and shaft slowly turns. Then, wrap one turn of rope around the pipe shaft. By pulling the rope tighter around the shaft, a great deal of pulling power is generated. If things go badly, just let up a bit and the rope slips on the shaft.
I wished I'd kept the gearbox when I sold the Gravely, as I'd like to do the same with my Ford Tractor PTO and 3PT mount of some kind.