Any size tractor that can carry the drivers weight on the 3ph safely will do. That probably means a tractor weighing 2K pounds or more. The hyd delivery is not very important just so youve got at least 1500psi. That pressure is necessary to lift the ram reliably. Lower flow will just slow the lift a little. The driver works by only the fall of the ram driven by gravity, so lo flow will just limit your blows per minute not the force of the blows. Even idling my 2010 JD lifts the 8D ram in about 2 sec since the lift only consumes about 1 pint of fluid.What is the smallest Mahindra tractor that one could use a post driver on. I'm thinking Shaver 8d using it on front or rear. Takes 4 gpm flow at 1500psi. The 10d needs 12gpm @1500psi