I AM NOT RECOMMENDING ANYTHING.
WHAT YOU DO WITH YOUR OWN CAR IS UP TO YOU.
I personally think the hype over DEX-III no longer being monitored by GM is a bit overblown. It's not like the specs are a secret or anything. And reputable companies (castrol, quaker state, penzoil, etc) are NOT going to make a fluid that says on the bottle it will work with a certain spec and then deliberately miss the spec. Oil is important, esp in a transmission where it has so many jobs (lubrication, cooling, hydraulic pressure, cleaning). Things start to blow up if you're off the spec too far.
I think that nearly all DEX-III labelled fluid from a reputable brand is going to be good quality fluid in every way that matters. Some will be better than others but all will be adequate.
It seems that the biggest difference between the ATF specs is the amount of friction modifier. The pre-modified oils are pretty much the same if you exclude the inherent differences between conventional and synthetics. That's my impression anyway.
DEX-III is basically NOT friction-modified, whereas most newer specs are (as most newer transmissions need it). There doesn't appear to be any danger in using friction modified fluids in transmissions that expect DEX-III-style unmodified/low-modified oils. There almost certainly is a danger in using a fluid like DEX-III in a transmission that expects highly-friction-modified oil.
Actually 'danger' is probably not a good word to use, because I think all the components would be protected, but the clutches/etc would grab too soon and too quickly making a jarring experience for the driver. But I think the transmission would probably be okay at least in the short term and if the driver wasn't really laying into the car.
I would personally think that ATF +4 is probably fine in a DEX-III transmission but I wouldn't use it because good quality DEX-III is so inexpensive. Even synthetic DEX-III fluid is a pretty good price these days.
This type of thing is discussed often at bobistheoilguy.com with some regularity and with some expertise. Here is one thread I pulled up with a quick search:
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1761280
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1998 V70 AWD->FWD->AWD Turbo 220k+
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