heater core leak question

[RTMagnum]

Hello All, what a great website. Lots of ultra cool chevy trucks in here. My first question has to do with the hot water valve in my 62 C10. As it turns out its the valve that is leaking. I was looking around on the LMC website and figured out that my truck has the deluxe heater in it cause it has four dash knobs. My question is about the hot water valve that I don`t seem to be able to locate on the LMC website. I`m guessing its no longer available.
What are your recommendations? Am I suppose to retrofit a different hot water valve? thanks