you could also get
this kind of valve, cable operated for temp control [prolly at NAPA], and keep the potential leaks outta the cab

I've tried in vain several times to find that same valve. If anyone has a source for it, I'd really appreciate it.
I would also like to find something like that!
oooh! I see a get rich scheme appearing!

I'll get the part number/source next time I talk to the guy, I'm sure it's off the shelf local, don't turn blue, might not be til next week

for the TF trucks [Chevy anyway, maybe GMC],
an exact replacement comes from
older Volvos, but I prefer a simpler manual control under the hood
Bill