I have finally had a look at this and from what I can see in all the images I have, the collar with the notch is only found on the last incarnation of the 119. This is the variation after the one you have, so it is possible that the collar has been replaced at some stage. Probably due to the standard cracking of the collar. Of course the collar with the notch could have been introduced just before the change and you don't see that combination very often. I am guessing that the change happened around 1956.