A38. 22x1 female spigot down
Links to photos of examples:
1978 Jawa 207 original
1979 Jawa 207 original
Jawa 207 with A38 installed with cover off
The chrome replacement Jawa petcock A38 is at left. Original is at right. The handle does not stick out of the hole in the side cover like the original did. So it is a little hard to reach but not too hard.