Quote Originally Posted by Rol_Lei Nut View Post
Older(?) version had a shutter release lock.

When I realized mine didn't have one, I felt cheated at the time, though in my model the advance lever does that when flush with the body (and I assume that the one with the coaxial lock didn't).
You're correct but Nikon called it a Shutter Operation Mode Selector. It does lock the shutter release but that is secondary (according to the manual). Its main function is selecting whether the camera is used with or without the motor drive. Evidently it was possible to damage the camera if it wasn't set to the MD position when using a motor. The trouble was that few owners were aware of that and failed to set it correctly so Nikon eliminated it in an updated version.