some pictures of an IDF 73363......with hands in pristine conditions and dial faded to dark brown.
the most interesting point to check in these IDF watches is the delivery number engraved in the back :
in all IDF watches I have seen ( from the very early Tudors with TWO digits delivery number up to the latest Heuers with
numbers in the range of 1900 ) numbers have been engraved by a drilling machine with round head.
so maybe we have numbers made with slightly different fonts ( depending on the time in which they have been made ) but they all have common features, such as :
1) very deep and large engravings ;
2) round signs at the bottom of the numbers ( that depends on the kind of tool ) , very clear in the points where the direction
of the number changes ( for ex. in the opposite points of the number "1" ) ;
3) flat bottom of the numbers with vertical surfaces at 90°.
the same kind of tool has been used also by the British MOD in the military SM 300 ( this is quite evident in watches given
to the Royal Navy ).