Welcome to CPF!
Actually, the 12ZM was never replaced.
The 12PM was replaced by the M4.
The 9ZT was replaced by the M3T.
I always regretted not getting the4 12ZM - I got the 12PM instead.
I would expect the 12ZM to sell for a price greater than that of an M4.
Is it possible you can post a photo of your 12ZM here? If you have a photo you can email it to me
[email protected] and I can post it for you.
The reason I ask is because the 12ZM/12PM were shipped with several different bezel types. Can you see the TurboHead bezel in this photo?
The N62 Lamp Assembly used by the 12ZM/12PM is extremely difficult to get hold of new.
The M4 uses the MN60 and MN61 Lamp Assemblies which may not produce the best possible beams in the 12ZM/12PM due to how bulbs and reflectors have evolved since the 12ZM was made. Chances are they'll work just fine though unless your 12ZM has a 3" diameter TurboHead bezel.
I prefer the MN61 beam over the MN60 when I'm not using the N62.
Thanks and enjoy your time here on CPF!
Al