Passage: Development of two production designs for the armys MGM-52 Lance short-range missile began in July 1964, the W63 at Livermore and the W64 at Los Alamos National Laboratory. Both entered phase three testing in July 1964, and the W64 was cancelled in favor of the W63 in September 1964. The W63 was in turn cancelled in November 1965 in favor of the W70 (Mod 0), a conventional design. By this time, the same concepts were being used to develop warheads for the Sprint (missile), an anti-ballistic missile (ABM), with Livermore designing the W65 and Los Alamos the W66. Both entered phase three testing in October 1965, but the W65 was cancelled in favor of the W66 in November 1968. Testing of the W66 was carried out in the late 1960s, and entered production in June 1974, the first neutron bomb to do so. Approximately 120 were built, with about 70 of these being on active duty during 1975 and 1976 as part of the Safeguard Program. When that program was shut down they were placed in storage, and eventually decommissioned in the early 1980s.
Of the missile designs mentioned, how many were cancelled? Which production designs were cancelled between 1964 and 1966?