A few things about this camera;
The top plate serial number engraving is not the standard usual look. The bulb symbol is not the old style (M2/M3) which it should be on this early version either so maybe the top plate is a replacement?
And the camera body has no self-time, and with the information data strip (you can see there the film rails area) of the 'medical' MD cameras, a few of the last M4s in black had this using the last parts of the 'classic' M-body, but I've never seen this with an early one.
Also the frame selector lever has a new style cap without the two holes to loosen it. Maybe a camera that's been put together from parts, or maybe this was a custom order/made camera?