The 356 was built in four distinct series, the original ("pre-A"), followed by the 356 A, 356 B, and finally the 356 C. To distinguish among the major revisions of the model, 356s are generally classified into a few major groups. The 356 coupés and "cabriolets" (soft-tops) built through 1955 are readily identifiable by their split (1948 to 1952) or bent (centre-creased, 1953 to 1955) windscreens. In late 1955 the 356 A appeared, with a curved windshield. The A was the first road going Porsche to offer the Carrera four-cam engine as an option. In late 1959 the T5 356 B appeared; followed by the redesigned T6 series 356 B in 1962. The final version was the 356 C, little changed from the late T6 B cars but disc brakes replaced the drums.
The last revision of the 356 was the 356 C introduced for the 1964 model year. It featured disc brakes all around, as well as an option for the most powerful pushrod engine Porsche had ever produced, the 95 hp (71 kW) "SC". Production of the 356 peaked at 14,151 cars in 1964, the year that its successor, the new 911, was introduced to the US market (it was introduced slightly earlier in Europe). The company continued to sell the 356 C in North America through 1965 as demand for the model remained quite strong in the early days of the heavier and more "civilized" 911. The last ten 356s (cabriolets) were assembled for the Dutch police force in March 1966 as 1965 models.
Source: Wikipedia (original)