It changes the angle of your engine, when you attach the chains to the front and back of the engine. So, you start out by picking up your motor/tranny, and make it level so that you can clear the front of your car. Then you crank it so the that the tailshaft is pointing downward, which allows you to get it into position easily. Then, as you move the motor backwards into position, you crank it the other way to raise the tailshaft back up as you are lowering the motor. Slips right in. Then, if needed, you can raise the tailshaft to let you get the tranny mount bolted up. Just like putting your foot in a shoe.