Rich the early Chronomatics are in the 1411/200 range and Heuer did not do many, also do these have a different case, lugs, pusher cutout and position.
Also some differences to the movement.
Have a look at pics onthedash you will see the difference.
Best Arno

: Jeff,

: Apologies for lack of response was out last night and been up in
: the old smoke watching Sienna Miller in a play (yes Master
: DeVos, she is as pretty in the flesh!). Flare Path is well worth
: a visit by the way...

: This Siffert is not a new addition, same one i have had for the
: past 5 or 6 months and posted a pic of before. Won in an
: auction.

: Arno

: I'm no Autavia expert like your good self, but it is the same case
: as the one in the Tag Heuer collection which is only 4 serial
: numbers away here are the numbers on the register...mine is
: under RC here...
: http://www.heuermonaco.co.uk/#/chronomatic-register/4542191890
: .

: As far as i can see - although my eyes are now 40 years old so they
: may be struggling to focus! - it has the same case as this one
: mentioned above that resides in the Tag Heuer museum?
: http://www.heuermonaco.co.uk/#/1163t-141378/4542651923 .

: My serial is 141374 the one at Tags museum is 141378.

: Tell me more mate...

: Cheers

: Rich
: www.heuermonaco.co.uk (clearly not an Autavia expert!)