What model Puch is your manual for? My Puch (1977 Newport (same as Maxi) single-speed) has a tag near the trans that says "use only ATF transmission fluid." Here's what I found after reading the transmission fluid bottles at the parts store:
ATF+ is designed for Chrysler transmissions.
Type F is designed for some Ford transmissions
Mercon III Dexron is designed for Chevrolet, Chrysler, Daimler-Benz, and most others exept Ford.
I know that Puch is a product of Daimler, so I'm guessing that the Mercon III Dexron would work. I don't know why Puch and Ford would be the only two to use one certain kind of trans fluid. Can you give me some more details from you manual? I think you might be missing something.
Thanks for bringing it to my attention, though.