I have only owned this since mid Nov. '17.... I am adding hot water heat to my '40 Standard. I have a '41 unit on the way..... I need to add a shut off valve to the passenger side head. It passenger side head has two ports on top with the forward one being a heat gauge sending unit that is inline with the driver's side head sending unit. The rear sender controls the electric cooling fan at the radiator. Do I eliminate the passenger side temp sending unit to add the shut-off or use a "T" to keep both the valve and the sending unit?