Found some nice fittings from chine that work on puch moped or any moped with 12mmx1mm thread gas tank.
they changed the site around a little but it says i ordered a 1/4" thread with a 8mm barb.... I know this sounds weird but it worked. I don't remember how I knew to order 1/4" ( parcel took over a month to arrive).
I checked on both a maxi gas tank & on a m12 axle and it threaded smooth!