I don't know what things cost where you are ,but a 4 x4x5 rock is fodder for a small dozer and at 55 to 70 bucks a hr for a rental or a contractor for 4 or 5 hrs work , that's small potatoes compared what it will cost you if you gut that little john deere tractor, sometimes you are better off to annie up and do what you need to do , instead of wasting who knows how much time and ending up spending 2/3 of what it would cost to have it done anyway, on trying different tactics.