EDIT... after re-reading the original post, I realize the poster is referring to type A fluid, not type F....
but the following still stands for those transmissions that calls for a type F fluid...
the original TYPE F trans fluid has NO other easy available options, unless you make up your own type F fluid....
ALL trans fluids EXCEPT type F has friction modifiers in them, and so it could make your transmission slip and overheat.....
I know this because I bought a boat with DEX III fluid in the trans which was suppose to have type F in it, and it overheated.
after a trans tear down and finding nothing wrong, I had to question the oil, since I KNOW the PO used dex III in it and had overheating issues for the last few years.
AND especially when the book says in capitol letters "USE ONLY TYPE F TRANSMISSION FLUID IN THIS TRANSMISSON"...... after calling the last 2 shops that sill work on these transmissions and talking to several people about it, I learned the information Im sharing here with you.
once I changed the oil to type F and running it a bit, the problems went away.... I changed it again a few engine hours later. and now after 300 engine hours, mostly at full throttle, there is no issues, whereas before the fix, we could hardly run at half throttle for 30mins without boiling the trans..... (oil would actually foam out the vent)
all im saying is... there is no trans fluid that will take the place of type F, when and if type F is actually needed for the particular application.
type F is still very much available, but not all auto parts store carry it, because most people think that dex 3,4,5 or 6 will take its place,... and so they just pour it in...
I dont know what trans you have, but I wouldnt take a chance... if it says used type F, get some type F fluid and use it.