Hi, as I am interested in the montblanc nibs from the 50ies I was wondering whether anybody knows whether the nibs + 'section' from the different series can be exchanged for each other. Specifically I am interested in the following : are the nibs & 'section' (I mean the part that is screwed inside the section) between the 254 and 264 series interchangeable?are the nibs & 'section' between the 254 and the 256 interchangeable?Many thanks for your help!! Lucas