Major Antifreeze Leak!

[Mallinson1@domain.elided]

Hi Gang-
	I had a development in my heater fix.  Unfortunately it's a bad one.  I
noticed an antifreeze smell driving this morning, looked at the passenger
floorboard and saw a wet streak coming down from the heater box where it meets
the firewall.  The next right turn I made had antifreeze POURING out of the
access hatch on the side of the box.  Literally, it looked like I was losing
3/4-1 cup on each turn.  It started splashing over to the driver's side and
was making the gas pedal slippery.  This is a bad thing.  I suspect the
regulator valve is faulty.  There aren't that many possibilities and I had the
core pressure tested before I reassembled.  The hoses are new with new hose
clamps, tightened securely.  So if the leak is NOT because of a faulty hose or
clamp the question is:  Does anyone have a part number for the valve assembly?
Or can the valve itself be replaced?  I think I found a NAPA valve for
Navistars (`72-78) that should work; the same parts book lists valve rebuild
kits, but with no description as to year/model, just listings by make (and of
course the parts guys can't tell me what they contain, though they are usually
very good.)  The regulator housing appears to be intact - I'm going to take it
to a radiator shop to be sure.  I'll probably take the whole heater box to
them.  And just when I thought I could move on to a new project...

Thanks,
Steve
======================
Steve Mallinson 
`62 C100 Pick-up
Still no heat or defrost, yet
Seattle, WA