I had to do this recently on my 85, the former owner had never used the
stove or fridge, so had never refilled the tank, and the bleeder screw was
completely frozen and broke off.  After numerous calls to RV places and
such, the answer came from my propane supplier, who sold me a regular
filler valve, I think it needs the 3/4" nipple rather than the 1-1/8"
nipple that goes on most large propane tanks, and a separate bleeder screw.
 Word is that the auto-fill was a bad idea anyway, besides being nearly
unavailable now.  Cost about $10 and took ten minutes, works great.