My thoughts would be:
-Mark is right in dating the watch around early 1972, pusher cutouts design of the case would conclude that
-Heuer had to give orders and numbers for the cases at least a year in advance
-Heuer was working closely with Piquerez, who developed the first square case designs water proof systems for the Monaco, you can read more about this in the next OM magazine in Italy
-Due to the planned Viceroy promotion the need for a second Autavia case supplier (Schmitz, see Jeffs post)became evident
-The Schmitz cases had a different case design, the pushers could be seen from the front and the back and another unique feature was the slightly domed backcase, compare with the Piquerez ( pushers only visible from the front and different slightly flatter caseback.
-For these Schmitz cases numbering started around 27xxxxx
-Now we could start to guess, why did heuer use a cal11/12 case for a 1563 watch ?
-Obviously the cal 15 signed cases have not been available at the time
-This specific dial design never appeared in the catalogs
-I know from time witnesses that the factory used what was available, especially after 1972 where nearly all cases were signed 1163 V and used for T and MH versions, similar to rolex 5512/13 and for example the diver 100 watches later using also V signed cases
-Therefore it would not surprise me if early Schmitz cases where used to do a limited run to test this dial design with the trade, there are quite a few of these watches appearing recently one is on chrono 24 from a german dealer.

Has somebody seen one of these appearing in the US ?

I have started working on an extensive Autavia piece, inputs and photos of watches very much appreciated..

Cheers

Arno

www.heuerchronographs.com

: Hello tiga,

: Well, I think this is a genuine and authentic Heuer Autavia. Looks
: indeed very strange but the overall look and detail gives me a
: comfortable feeling. However this could be some kind of a
: prototype or a model with some very very low production.
: Ofcourse this is my personal opinion and I do not pretend it to
: be the only truth.

: I was also present at the first Heuer Collectors Summit in May
: 2008. When we were visiting the workshop where they
: handle/service the vintage watches there was a little
: "Presentation showroom" where some vintage Heuer
: watches were shown. Between those watches there was exactly
: thesame Autavia exposed as yours, so I think you can be pretty
: sure about originality.

: Here are two pictures of that "Presentation showroom" I'm
: talking about (also David already mentioned this ofcourse). The
: pictures are not very good but if you have a good eye you can
: see exactly thesame caliber 15 Autavia dating from 1978, just
: above at the right side from the McQueen Monaco.

:
:
:
:

: I hope this helps.

: Have a great weekend,
: Abel.