Until 1962 the Stratocasters were equipped with CRL 1452 3-way switches (where CRL stands for Centralab), consisting of a metal support and a round wheel with a squared crown holding the switch contacts, both made of a dark brown fibrous material. On the front metal facade three patent numbers - "PATS 2291516 2291517 2503885" - and "MADE IN U.S.A." were engraved, not always clearly visible due to oxidation, while on the back there was the engraving "CRL 1452".
The tips of the first 1954 switches had an oval shape, hence the nickname of rugby tip or football tip. At the end of the same year the knob changed its shape and was nicknamed pear tip. 

1954 CRL 1452 with tre patent numbers and made in USA engravings

The other side of a CRL 1452, 1956 (Courtesy of Nino Fazio, realvintage.it)

Rugby Tip

Pear Tip

Between the end of 1962 and the first months of 1963 the new Centralab 1452 selector gradually replaced the previous one. The new 3-way selector was smaller, had an outer fibrous crown with rounded edges to form a semicircle, while the central wheel was in white plastic.
At first the patent numbers were still three, but in a short time they were reduced to only "2503885". Moreover, since 1965 a diamond-shaped logo had been sometimes engraved, and it would have always been there since the early 1970s. It seems that the CRL 1452 switches from the '70s, despite the engraving, were only assembled in the United States, while the components came from Japan.
Only in 1977 Fender started to use for the Stratocasters the five ways switch. 

CRL 1452 used between late 1962 and 1964 had a white heel and, useually, three patent numbers, two extra little holes and no diamond logo

1972 Switch with the diamond logo on the left (Courtesy of Nino Fazio, realvintage.it)

Other "alternative" switches were also used, very rare because Fender bought very few, such as the CRL 220-283 (with square edges) or the CRL 220-288 (from mid-1964).