Heater valve?

[Wallace White <wallace@remdesign.com>]

My heater valve lived up to its reputation this afternoon. The two
halves of it split apart while I was sitting in line for the baseball
game. I shut it down pretty quick and refilled the tank with water while
the after-run system (with working pump, thank goodness) ran like a
champ. But there I was, stuck, thinking of Dave Head's and Steve
Buchholz's recent messages about carrying plugs and flush-n-fill kits...
while my trunk had none.

I happened to get towed to near my office, so I'm looking for heater
valve help. The nearby Kragen doesn't have the right valve in stock.
I'll look for a flush-n-fill kit. Maybe I'll even turn a piece of pipe
the right size, since I'm here at work. But I remember talk of a
non-Audi replacement heater valve--from NAPA, perhaps?--that was an
upgrade. What is it? Can I get it from stores besides NAPA?

Thanks for your help.

- Wallace
  '87 5kcstq 155k