Hi Ben

In my opinion if the oil you are using works for you, then use it, Better to use something that works and you can change regularly.

There is nothing HI-Tec in those gearboxes.

I have used ATF in my gassers for about three years and that is cheap enough and I get good clutch feel, and can stop and find nuetral when I need to.

Others will say different, but it works for me.

TLTEL (by the way mine are not the pro model)

DEXRON III is synthetic (DEXRON II is mineral)

So the above seems a bit of a Contradiction?

The difference is oil vs fluid (transmission in this case). They are not the same, so synthetic in one is not like synthetic in the other.