A4. 10x1 male spigot left
Links to photos of examples:
Any top-tank model, with a 10 x 1 threaded hole on the right side (and nothing nearby) would use this A4 petcock.
Motobecane: This spigot-left valve fits 1970’s sheet-metal-frame Motobecanes, where there is a tight space. It substitutes for the spigot-back original configuration. The fuel hose is routed slightly better than it was with the original valve. See above valve A3.