Based upon the catalogs. this is the timeline for Aqualung cylinder valves:
1953-1974: 1/2" tapered thread valves available for purchase.
1960 is the last year that the 1/2" R valve and the venerable 1/2" triples manifold are offered.
1960-1962: 3/4" "J60" and "k60" valves debut. These valves do not appear in the catalogs after the 1962 catalog. The 3/4" doubles manifold with J valve debuts. All of these valves feature the knob on the top.
1963-1973: 3/4" "all metal" style valves debut. The line up features a J valve, a K valve, a "sonic" J valve, and a doubles manifold with J valve. These valves look like a modern style valve, with the knob on the side.
1965 is the last year for the sonic J valve.
1974-present: 3/4" plastic knob valves. These look functionally identical to the "all metal" valve, but they feature the now common black plastic knob and J valve actuator. They still include J valve, K valve, and doubles manifold.