That's another interesting point David.

Take a look at my post here -
http://www.chronocentric.com/forums/heuer/index.cgi?page=1;md=read;id=38609

I had a bit of a chat with Bullitt from the Italian forum about this and we discovered there are 2 types of Schmitz style cases (cutouts front and rear) with very minor differences.
Early 14* serial numbers with angled 'shoulders' on the lugs, an extra bearing under the bezel at 7 o'clock, no 'V' after the 1163 between the lugs.
The later 2* don't have such a pronounced angle, the few I've seen don't have the bearing and they do have a 'V' between the lugs.

My 14* (early Siffert dial, hands and C11) also came with a 69 G/F bracelet with HLD end-pieces which look right on the angled lugs.
HLF end-pieces don't look right on it...

Incidentally, ever compared the lug-holes on a few 11630 cases?
I've successfully managed to spear myself in the hand several times trying to get a G/F bracelet on one that easily went on another...

Cheers,
AndyO...

: As a footnote to the different cases point that Paul has made, I
: have found that the case lugs are different depths too, dial to
: case-back.

: I found this out when I tried to put the GF bracelet from my 1163
: MH 'Bell' on to my 1163 T 'Siffert'. It wouldn't fit as the Bell
: case used HLD ends and the Siffert used the slightly deper HLF
: ends.

: David H