Well, here it is . . . the dodecagon-back Carrera, with the nice big (low) serial number!!

More on the dodecagon, here -- http://en.wikipedia.org/wiki/Dodecagon

Jeff

++++++++++++++++++++

: Thanks for the answer Mark, it clears up alot of things.

: I don't have the watch in front of me (in the bank safe) but it is
: certainly not a hex back, particularly as you so rightly point
: out, Heuer never made any watch with a hex back, but neither is
: it a poly back*, it is a circular style back - I'll post a pic
: when I get the watch back home. The inside is Ed Heuer rather
: than Heuer Leonidas. This matches your theory of running out of
: the standard backs at the 54xxx range.

: Do you agree also with the larger font on the serial number for the
: 53xxx range?

: Shaun

: * if we want to go super pedantic, then the circular back could be
: considered also a poly back with an infinite number of sides.