A22. 12x1 female spigot right long shaft
Links to photos of examples:
1978 Benelli G2, A22 is too long
Benelli G2 This A22 valve has a round aluminum shaft that is 56mm long, too long for a Benelli G2 or Moto Guzzi Robin. It needs to be 15 to 25mm shorter. Use A20.