Let me tell a true story. A friend of mine was home during Christmas vacation and he kept busy hauling logs out of the woods with a tractor something like the Ford 9N I think. He went back to school with one more log left to go. So his dad went to get the last one. They found him pinned under a tractor that had flipped up over backwards. Dead of course.
Look at the photos posted above posted by Piker. Only one of his photos show pulling from a low (but not the lowest) point. Most show a chain attached from well above the rear axle, pointing in a direction well above the rear axle.
Think of the rear axle as the pivot of a teeter totter. However, instead of just weights on each end of the board, only one board end has a weight, that being the center of gravity weight, located forward of the axle, providing a twist in the direction toward the front. Looking at the axle from the right side that is a clockwise twist.
On the other end of the teeter totter is only a vertical bar with some force holding it back from a location higher than the axle. This is that three point thing shown in the photos. Note that it tends to twist the opposite direction than the center of gravity, counter clockwise. Also, attached to the teeter totter center axle is a powered device wanting to take it towards the center of gravity end, that being the tractor's forward force. It is twisting the tractor body in a counter clockwise direction.
Thus you now have three twisting forces working on this "teeter totter". The center of gravity with clockwise twist and two factors providing counter clockwise twisting. If these counter-clockwise twists exceed the clockwise twists, well, that spell ls trouble.
That explains the lifting of the front as you pull as shown in the photos. Do enough counterclockwise twist in these directions and over she goes to the rear.
You can minimize the dangerous twist by changing the way you hook onto the tractor. You can't change the other stuff other than putting more weight in the center of gravity side. So, with most tractors there is a draw bar that is LOWER than the rear axle. Using the draw bar then this applies a twist in the direction the same as the center of gravity,on the safe side.
In summary, any one hooking up to the tractor as shown in the photos with the chain aimed up over the axle is asking for a risky operation. If you do use the rig that Piker shows in the top separate photo with the chain through the 2" trailer hitch thing, set that three point thing down below the level of the axle. Now I will admit to hauling lots of logs with the three point attachments, I made it a point to keep that hauling point as low as possible.
Just keep in mind these three twists as you haul logs. You can only change one.
