Back in the early 1970s, production was a bit helter-skelter, with no clean breaks between "model years" or specific executions, and we imagine that Heuer was using whatever parts might have been available. It is interesting (and comforting) to see another 11630 GMT with the 262xxx serial number and the Caliber 11 movement.

Simplest explanation -- When Heuer was producing these 262xxx 11630 GMT watches, they came upon some unused Caliber 11 GMT movements and used them in these watches.

Jeff

++++++++++++++++++++++++++++++

: Hi Frank, welcome to OTD. You are correct that it is unusual to see
: a (modified) calibre 11 in a GMT but not unheard of. It is
: recognised that the early 1163 GMTs used the cal.11 but there do
: also seem a few 11630s that used it also-a couple of which can
: be seen here-

:
: http://www.chronocentric.com/forums/heuer/index.cgi?md=read;id=86957

: and here-

: https://www.bonhams.com/auctions/24883/lot/55/

: the latter being the most interesting as the serial is also 262xxx.

: So while not being the norm, it is not totally unique in that
: sense.

: Hope that helps,
: Steve