Do you know where to find more specific information so that when one is looking at photos (or in person) of a 146 you stand a chance of guessing the rough date. To me, it's hard to tell whether its resin or celluloid, but I can sure see a nib with 14K or 14C (but don't know what year that changed).
The material the pen is made out of. The type of feed. The piston mechanism. If you look at the dating the 149 sticky you can use it as a rough guide to dating a 146 as well
With the 146 (as well as 144 and 142) you need to remember that there is about a decade gap when Montblanc didn't make those models.
A 142 or 144 that is piston filled will be from the first generation and made from celluloid. They will also have a concave section.
A 146 that measures about 135mm closed will be a first generation and also have a concave section.
Those pens would have been made between 1949 and the very late 1950s.
Then the 14x series was discontinued with the exception of the 149 that continued in production.
In the early to mid 70s the 146 and 144 returned to the lineup. The 146 was still a piston filler but the bodies were resin and it had grown to a length of about 143mm when closed. All the sections were now flat. The 144 was now a cartridge/converter.
IIRC the change to the "K" designation instead of "C" happened around the mid 1980s.