Here's a Ref 1002. No date Oyster Perpetual chronometer, 34mm case:

Name:  rolex 1002.JPG
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Here's a Ref 1018. Same specs,except 36mm case.

Name:  Rolex 1018.JPG
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Both were made throughout the sixties. The 34mm was made until 1987ish. The 36mm seems to have been stopped earlier (stepping on the Explorer's toes?) When I came to write this I thought they were stopped c.1970, but I've just seen an advert for one made in 1978.

Does anyone know when they stopped making the 1018?

I'll be continuing to google