I am thinking the really old US PSTs are the same and will try and compare them when I get home
Another interesting JPST arrived today. This one doesn't have any stamps on the knife blade, I've never seen it before.
Another rarity - presumably a factory error.
I think it's not error, it's standard variant of knife blade, but much more rare than the other (with stamps on tang) variants.USPSTs also have such blades: