With the introduction of the new, slimmer shapes designed by Albrecht Graf Goertz in 1959, production of the Meisterstück 142, 144 and 146 was discontinued; only the 149 continued. In 1969/70 the Goertz models received a flat cap top and new numbers (e.g. 320, 220, 120). In 1979 the gradual reintroduction of the classic design began; the Meisterstück 146 was officially relaunched in 1986 — although 1970s-era 146s are known, indicating transitional models. Current Meisterstücks are formally based on the 1950s predecessors but technically and materially considerably modernised. The 144 was later marketed as the Classique and discontinued some years ago; early Classique models sometimes still had no serial number.
Related pages on fountainpen.de:
• Montblanc Meisterstück 146 (Le Grand): https://www.fountainpen.de/c-montblanc-meisterstueck-146-en.htm