you wrote, "BTW: what came first, this carrera skipper or the 2446 autavia cased one shown in AMH's book?" I am fairly certain that the Carrera-cased Skipper was the first Skipper (mid-1960's), to be followed by the 2446C-cased version of the Skipper (later in the 1960's). I will attempt to confirm this.

I agree that there is much to learn, as the "one-offs" and limited runs of certain models can make it difficult to be certain which ones were made by Heuer, and which came with other people making watches from the parts bins. I believe that other brands had this same phenomenon. For example, I have tried to learn the sequence and variations of the early Rolex Explorers (black dial / white dial; white marking / gilt marking; textured dial / gloss dial; many styles of markers and hands), and it makes the Heuer patterns seem simple. Back then (1950's and 1960's), they seemed to create new models in a fairly haphazard fashion . . . indeed, it seems that the manufacturers often used the parts bins to create the first versions!!

Jeff