Originally it would have used Dexron II. Dexron II has been replaced by DexronIII/Mercon and that's what you should use now.
Better or not, really isn't the question. Dexron-II has been replaced by Dexron-III. Any transmission that used Dexron-II can now use Dexron-III. Fluids labeled Dexron-III/Mercon are also acceptable.
If it is a A/T Powerglide, you can use Dexron or a synthetic such as Mobil 1 ATF. You may not be able to find Dexron, but you can use Dexron II or Dexron III.
Honda originally specified Dexron II for that transmission. Dexron II no longer exists, as it was later superceded by Dexron III. So, use Dexron III. You will frequently see bottles of ATF that say "Dexron III/Mercon" or "Dex/Merc" for short. That's the stuff to use.
Use Dexron III instead of Dexron II that is recommended for this vehicle .The tray takes about 1.7 liter. Do not forget to replace the filter. Good luck !
Dexron II originally in 1970. If you're buying fluid for it now you won't likely find any Dexron II as it has been replaced by Dexron III/Mercon fluid and that's what you'll use now.
DEXRON II or III
Dexron III/Mercon automotive transmission fluid (ATF) is generally recommended as a replacement fluid for automatic transmissions meeting original equipment manufacturers (O.E.M.) performance requirements for current General Motors, Ford, other domestic and imported passenger cars, vans and light trucks where DEXRON II, DEXRON II-E, DEXRON III, AND Ford/MERCON fluids are specified.Dexron VI is a partial synthetic which properties exceed dexron III by 100% in every area. Dexron VI can not be interchanged or repalced with DEXRON II, DEXRON II-E, DEXRON III, DEXRON-III/MERCON.
Dexron II or III with Mercon.
Dexron II
Use Dexron II transmission fluid.
Use Dexron-VI. This replaces Dexron II which was formerly used in your S-10.