Ok, are you ready for this? Let's get super simple. Throw your left hand (overhand) with your right arm. Imagine your left hand is a baseball and you're throwing that baseball with your right arm toward the target.
You'll do this overhand so it'll feel like your right hand it above your right shoulder. Yeah, above! It won't be above the right shoulder in relation to the ground but it will in relation to the shoulder plane.
When you throw a baseball your right forearm is not parallel to your spine angle it's open and angled outward. When you bend forward properly toward the ball this will be a perfect strike pose.
Hold the club with your left hand,, throw your left hand with your right arm and forget all about the club. The club should whip through the hitting zone with effortless speed.
I think this is what Jim Furyk is doing with his 2 finger overlap grip. Furyk's 2 finger overlap may enable you to get the feeling of throwing the left hand with the right arm.
We all know how to throw a ball and we do it without thinking. What happens is we're using the forearm as a cantilever to whip the hand around. When you swing this way you're just thinking throw the left hand, not swing the club
When you swing down at the ball that forces your shoulders up and your hips forward toward the ball. Basically, if you swing down you have to stand up as you do it.
When you throw the club overhanded, over your right shoulder, you have to bend and tilt and twist as you strike the ball.
Watch Fred Couples Swing below as well