"paint - nice thick stuff that seems to fill in engraved info nicely" Some automotive brake cleaner should clean that paint out very quickly. Or, some gel stripper left on for a while, following with a wire brush or "acid" brush (stiff plastic).
IIRC the 3H and 3G series use different transmissions so the same fluid might kill one or both. Dexron has been obsoleted, I think they are up to Dexron-IV by now. But using the wrong type of ATF fluid can ruin a transmission or the seals in it, so you'd want to make Real Damn Sure before adding anything to it.