I see this post has been going on for some time, I seem to have more to contribute. Good thing I searched!
I just received some early Z parts , and in the box was an interior mirror with a dimmer of type not mentioned above.
It has a lever to push side to side, rather than a knob to rotate, with a moon and a sun on either side of the lever face. The body of the mirror has a slight indent where the level is recessed (slightly) to stop it left and right.
The owner of the parts claimed that some part were from a 70.
Its in great shape, the mirror is nearly perfect, the black on the back is slightly faded, but no plastic deterioration that I can see. A little SEM and its going to be like new.
Any one ever hear of this type of mirror in a 240?