remember mariner, if your practice swing and real swing are different, it is because of your set up.
but if you want a drill try this,
tee up balls with a six iron, go to the finish position that you want to attain and feel where that is
then your objective when you swing is to swing to that position, you are not worried about the ball, where it is, where it goes, you are just swinging to that position as fast as you can and the ball gets in the way