Interesting about the Style C that these were signed by Lucas and Kurtz. Although the Style C without the ratings box is referred to as the International style, it was used in some US theaters. I know for a fact it was used in the Brookdale Plitt theater in Brooklyn Center, MN in 1978 as a friend of mine actually got the poster they used there. It was also tri-folded. Is it possible the studio was distributing these to theaters? If so, what was the PG version used for? Military bases is one theory, special screenings is another, but no one seems to know for sure.
Clearly the studio had a supply of these tri-folded Style C "International" one-sheets as is further evidenced by this find, and somebody was distributing some of them to US theaters for use.