ok Donald, the Bennett manual says "any ATF". Now Dex3 is an ATF, right?
Yes, DEX III is an ATF, although officially GM withdrew licensing for the DeEX III spec so no one can claim they are DEX III anymore, but many still do. The current GM spec is for DEX VI.
I would use any DEX III or above ATF except maybe some real cheap stuff from the dollar store. The trim tab application is no where as tough as the transmission application.
Dexron-II (and Dexron-IIE) are long obsolete automatic transmisson fluid specs. They were replaced with the Dexron-III spec, which is almost 100% compatible (older Hondas are the only transmissions I know of that need Honda's own ATF to replace Dex-II rather than using Dex-III).
Dexron-III is now an obsolete spec replaced only in GM Hydramatic transmissions by Dexron-VI. Yes, most ATF blenders still produce a product to the Dex-III spec under a somewhat similar name, maybe Mer-Dex or D-M or something.
GM still licenses the same ATF formula under different names...Allison TES-389 and some GM manual transmission fluid name.