Got to disagree here... I did lots of research on this one.
You should go with Dexron Mercon...even though the original was Type "F". It seems that the Type "F" will eat the rubber seals over time, where the Dexron Mercon will not. Both do the same job. The Type "F" has properties in it which do not like rubber...
I vote Dexron Mercon....Which is what I have in my pump.. Works perfect.. I would suppose this is the reason that they went away from the Type "F" fluid over the years, but I am not a chemist obviously.