Mark, I guess it could be the other way around as obviously unsigned generic crowns were easier to source during servicing.
Also Camaro uses all signed crowns since the watch introduction.
What do you mean with second generation Carreras, for me the second generation starts with the product changes after hexacase, pushers, dial...
Have a look at meertz site with the two Carreras, hexa and next gen, there are a lot of learnings in there for our readers...
Who can identify all the differences ;-))
http://www.worldoftime.de/de/uhr/heuer.3536
http://www.worldoftime.de/de/uhr/heuer.4105
Cheers
Arno

: It's not like that for Carreras. Autavias were carrying signed
: crowns long before they started on the Carreras, whether 12s or
: 45s. Certainly none of the Carreras were introduced with signed
: crowns in first execution and we don't see every example being
: fitted with a signed crown until, as I said earlier, the second
: execution.

: We do see a number of first execution Carreras with signed crowns
: and I think some of these are factory fitted, but I think some
: are also later additions. Certainly if a watch was going back to
: the factory for revision that required a new crown post about
: 1970, a signed one was fitted as the unsigned ones no longer
: appeared to be stocked.

: Take a look at some of the signed crowns fitted to early Carreras -
: sometimes they are thicker than they should be, and these ones
: look to have found their way from Autavias onto Carreras. I
: believe the stem and tube are the same diameter for both
: watches, but the crown is physically thicker for the Autavia to
: match the larger watch.

: As a personal rule of thumb, I am generally happy to take an
: unsigned crown on an early Carrera at face value, but if the
: crown is signed, I will look more closely to see if I can tell
: it is original.