the 1955 Ford T-Bird documentation says to use Type "A" transmission fluid which is no longer available. I am in the process of of restoring the car and I am looking for advise on what transmission fluid is compatible with the clutches and valves of this original transmission. What fluid is best? What will work?

Type A may have been replaced by type "F". If you try any of that newer Dextron/Mercon crap you're likely to end up with headaches after a few miles.