Nice observation Ron.

We know the date at 12 original Dato 45 was only produced for a period of less than a year over 66/67. The version with the date at 9 then appears in catalogues in 68, 69 and 70, which gives us an idea of the total lifespan.

As to which came first, the version with the white date window inner or the one with the black, I have to confess I really don't know! I wonder if at some point they decided that having different parts for this inner on the S and N dials was an unnecessary extravagance and settled on the white inner for both. As this could conceivably have been at the start or the end of production though, I think Jeff's asking for serials is about the only way we might be able to settle it. This being Heuer, they could just have used what was in stock at the time and we could end up seeing it switch back and forth throughout production. All adds to the fun as far as I'm concerned!