Thanks to the detective work of Steve (servicide blogspot) !
1957 1/2 - 1958 International Travelall.
The 1957 1/2 "A-Line" (A-100s) was totally redesigned for International's , and replaced the S-series nomenclature (the 'A' stood for Anniversary). Although the styling held over for the 1958 model year, I believe that only the '57 1/2s were considered Golden Anniversary models. Travelalls and panels had one door on the driver side, and two on the passenger side.
The basic body style held over for 1959-60 also, but with grill, trim, and headlight changes.