A2 Petcock

A2. 10x1 male spigot down

A2 10×1 spigot down
01z2231010   $15
←reserve on↓ off→
made in Italy by OMG

A2b 10×1 down
red handle  $16
←res  on↓ off→

Links to photos of examples:

1977 Pacer P14
1977 Negrini Harvard replacement
1977 Cimatti City Bike (when adapter is missing)
1978 Cimatti City Bike (with no 10-12 adapter)
1978 Motron original (extender on tank)
1978 Concord XKE original
1980 Peugeot 103 LVS replacement

This valve fits hundreds of mopeds and mini-cycles. It fits any tank with a 10×1 threaded hole, and with nothing below or near the valve that would interfere. 

Cimatti rear tanks have a 10×1 threaded hole, but there is a nearby “wall” that prevents a 10×1 male valve from screwing in, unless the whole gas tank is removed. That requires rear wheel and rear fender removal. To make gas valve installation easy, Cimatti added a screw-in 10-to-12 adaptor piece, and used a 12×1 female type gas valve, with a turnbuckle type nut. Only the nut turns, and the “wall” does not matter. So it is much better to reuse the 10-to-12 adaptor, and use a 12×1 spigot right valve, see below.