Northernmainer is on to something with the pin height. When you pin a plow onto a pickup, on level ground the main plow frame is horizontal or slightly downhill at the plow end. It should sit that way on your tractor. With the tractor, you can raise or lower the pins (loader frame) and change the angle of attack. That's useful when the drive is soft, as lowering the loader lets the cutting edge rise, pivoting on the shoes. When the ground is frozen, you can raise the loader and increase the cutting action of the edge. Loader is also useful if your drive isn't flat, as you can keep a constant angle of attack if you're willing to fiddle with loader height.
Jim
