great watch !! my first idea would be: it was at Tag Heuer for a center recase and bezel ?
Does the backcase show some polishing ?
Aprox.seven years ago new old stock Heuer Autavia (MH, Skipper, Decom., all later 70 series, no 1163)and Calculator cases appeared at munich watchshow, the came in boxes of five rather mixed, none of these had serial and reference numbers.
I think they were 70€ per piece, around 50 cases, I dont recall who bought them finally...

Cheers

Arno
www.heuerchronographs.com

: Hello,

: This is my latest arrival. A very nice and 99,9% NOS 11630MH
: Autavia. Strange thing about this one is that it has completely
: no serial or model number stamped into the case. So nothing
: between the lugs. There only is a C-xxxx-x number engraved on
: the caseback. As already known (some) Heuer watches distributed
: to the Swiss watchmarket came with this "C-xxxx-x"
: number engraved on the caseback.

: As stated before I was quite surprised there was no serial or
: modelnumber at all present on the case...Arno, maybe you know
: why??

: Here are already some quick pictures;
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: Cheers,
: Abel.