Type T-IV trans. fluid

[mykngdom4avvti]

Question:
Many of you may know that Toyota has been putting a new type of tranny fluid in many of there automatics for about three or four years. It smells terrible and is dark red in color.
Anyways, Ive done some research and asked a few insiders but nobody can give me a for sure answer on this,

"Can you use T-IV in an older Toyota recommending Dextron?

The reason I ask is because Im told it is a better fluid and contains friction modifiers.

[repinS]

I've heard some things that T-IV is not recommended for older gearboxes.

There are Cressida drivers with the A340DE (Dexron recommended) transmission that swear by T-IV.

Contradicting things.

[ekpolk]

And just when you thought you might have started to figure this out -- Toyota comes out with another ATF. From what I've heard, in some '05 models, there will be a "world standard" or WS fluid used. Anyone know about this stuff?