Same note, diffent header... Interesting discussion friends and I admire all this knowledge.
Now here's my case: In my hands I have an original delivery note
from Heuer Leonidas SA, Rue Veresius 18, Bielle, Switzerland
dated 6.2.1975 It is an originally hand-typed price of paper.I
received it with this watch 2 yrs ago. It carries the following
text:

votre envoi du : 13.1.1975
Ref No: 1133N/11
Boite: 161816
Remis en etat: 1 chronographe, change de mouvement/ Service
Garantie

Doesn't this mean that a Monaco 1133N ( case no. 161816) has had
its calibre changed unter warranty early 1975? Wouldn't this
mean that the watch was most likely built after 1971 ( warranty
case) The 1133N code was clarified to me my Jean Jacques Racine,
Heuer's Chief Watchmaker in the old days who confirmed during
our visit past May 2008 that the Monaco with all-grey dial ( so
no subdials with different shade of grey) was internally called
1133N at Heuer.Or aren't non-1133B Monacos not part of this
analysis. Greetings!!! Ron