I dont know where to get ont but about 15 years ago I had a pole barn built and the builder had a 60-70 hp tractor with a post hole digger on back , the tractor had a rollbar and betwween the top of the rollbar and the digger was a hyd cylinder. I think it was homemade but it really worked. We had some tough digging and he could lift the back wheels of the tractor off the ground so all that wieght went on the digger