Deffo in range for late 1966 105.003-65 but that has been serviced to hell. There is a dial on ebay right now but the seller is asking I think £4000 so good luck in making the sums work!
You establish the movement serial and check here:
https://www.ilovemyspeedmaster.com/productiondateprediction/
and more importantly here:
http://www.moonwatchonly.com
Or do what many do here and learn the nuances of the various models and identify them by sight!
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