It has been about 12 years since I first installed my 3rd function. I have a new tractor so I have to do it again. There is something I cannot remember about the valve. I have an open system. For a grapple, do I need a tandem center valve or open center. If my memory serves me, and it usually doesn't, a tandem center will allow the work ports to stay shut thus keeping the grappled closed with tension. With an open center valve, pressure will release when I go to neutral (not push the button)? Am I correct?