: Very unusual, it most likely incorrect, however I have seen this
: type of Valjoux 72 with some brass parts before, so it is not
: 100% out of the question, but we would need to know more
: info....

: What is the code on the bottom left hand side of the base plate?
: There should be R for Valjoux and 72 for the movement on the
: right side and then normally MN on the left. It is normally MN
: on Valjoux 72 (1st execution Ed Heuer Autavia 2446 and the very
: earliest Ed Heuer Carrera 2447 are the exception whereby there
: is no two letter code).

: However I have now seen two original Carrera 2447 with AR on the
: base plate with brass Heuer Leonidas bridges which have the
: words "Seventeen 17 Jewels Unadjusted, Swiss" also on
: the bridge, instead of on the left hand side of the plate. (AR
: is the code for Enicar). Yours has no "17 Jewels" info
: though.

: I am told that the some watchmakers constructed watches for both
: companies. It was a cottage industry back then, some Enicar were
: even constructed at Heuer in Switzerland and also in busy times
: much work was done "overtime" at watchmakers houses
: also including their relatives also.

: R

As promised, picture of the codes below the balance wheel. Indeed a Valjoux 72 but with AR coding. So now whether as stated there could have been built Heuers with Enicar parts, I guess it could be possible but more units should be documented to ensure more reliability on this. If it is true for Carreras, why not for Autavias?

Many thanks again for all the comments.