I think he's referring to the original MP, based on the M3, several copies of which were made for prominent photojournalists in the late '50's. I think they were black paint and had a hand winder on the bottom of the camera.
They are worth an awful lot of money today.
What I don't get is that the current MP should be the same size as the original MP since it doesn't have a taller top plate since it doesn't have ttl circuitry, like the M6TTL or M7 do.