If you have a F in the 658xxxx or 659xxxx range, please email me the serial number and whether or not it's a Red Dot. I presently believe all 66 F bodies are Red Dots. The accepted story is that Nikon realized it made a mistake in re-using the 66 block previously used for the S3M, and so switched to the 67 block. However this story makes no sense to me, since Nikon previously re-used the 65 block from the Nikon S4. According to Nikon, no black 66 body ever left the factory.
More research needs to be done on the production.
If you have 66 Nikon F, please email me the serial number. The F was produced several years after the introduction of the F2. In the late 73 range, F cosmetics were upgraded to match those of the new F2, including F2 styled plastic tipped winding levers, plastic tipped self timer, and threaded PC outlets. Again, production does not seem to be continuous. More research needs to be done on the production.