[skyking]

the line of force is below the centerline of the rear axle, so that pulling force will impart a downforce on the front axle.
here is a story of the opposite effect.
When I was 15 we cleared a 23 acre orchard. We had a big cat take all the stumps out but left them in place so we could tow them down with the farm tractors. We had '52 silver jubilee 8N ford, and a little '72 mitsubishi diesel.
To get the stumps started in the loose dirt, we rigged to the top point of a 3 point hitch so it would tend to lift up a little as well as pull horizontally. This is WAY above the axle centerline.
I was towing a big stump down to the burn pile with the mitsubishi and I ran across the loose dirt where the dozer had filled a stump hole.
In an instant, the stump dug in and the front came up on that tractor. I was ejected off the back and rolled away to keep from getting crushed.
The tractor was sitting there in 5th gear wide open throttle, digging two holes. The same physics of where the forces were applied kept it from flipping clear over onto me. It was standing straight on it's tail
I cut the throttle and killed it, and we pulled down on the front end till it was upright.
Oh and I cleared out my underwear. :P