I am looking for the valve that regulates the heat flow to each side ( i think) part number JGE000010 which is number 8 on here http://www.rimmerbros.co.uk/Item--i-GRID004237

My one on my rescue car is missing completely as at some point it must have been taken. Not sure if there is a way around this at all as there was some talk of a T piece but I assumed I needed the part there to do this...