Mustang production began in April 1964. For various reasons, including a lack of parts due to overwhelming demand, it stopped in June 1964. The cars built during those first 3 months are identified by collectors as 1964 1/2 although they are all registered as 1965 cars.
Production resumed in September 1964 with a series of upgrades including new engine options, minor cosmetic changes, and generators replaced by alternators. These are regarded as 1965 models.
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