dextron has a higher heat range before it gives out. learned that in
a bus garage that had hundreds of automatics in the fleet.. since i been
useing dextron in old fords with no troubles.lucas

http://www.minibite.com/america/malone.htm

I'm not sure about the "heat range", but I'm told Type F has slightly
different friction characteristics. I worked in a local trans shop for
a few years in the mid-80s, and we used Type F for all US made
automatic transmissions ( common 3 speed automatics and early ODs
then). The shop was highly trusted and had an excellent reputation,
unlike many.
Our builder told me, in a nutshell,  that Type F was formulated to
have a bit higher coefficient of friction (not sure if that's the
proper term or the one that he used. I's not as "slippery"). It was
specified by Ford because the engineers felt Dexron didn't have quite
the properties they were looking for. Type F reduced slippage as the
bands\clutches were being applied and raised the gripping force on the
bands\clutch packs slightly.  The difference between the 2 isn't
large, though.
That is highly simplified, but you get the idea. The difference IS
noticeable. I found that older GM transmissions shift a bit firmer
with Type F. I seem to recall that most shift kits recommended Type F
for non-Ford applications.

The waters muddy a bit these days. Type F became Mercon III, I think.
Then there was Mercon IV. Then along came Mercon V which is (semi?)
synthetic. GM and Chrysler had their own iterations that may or may
not be compatible. Today, you always want to carefully follow the
manufacturers recommendations for ATF.

Hope this helps clear things up a bit. Maybe someone can explain the
difference in-depth.
Regards, Tom

OBTW, The correct name is Dexron. No "T".

Yet, since the internet came out, you have yet to find the web sites
called "Google" and "Yahoo."