The only difference in the SP and S3 is the viewfinder. The S3 uses etched framelines, rather than the projected lines found on the SP. This results cosmetically in the more traditional finder window, and functionally in all of the frame lines being present in the finder at all times. This is actually quite annoying in use, and the difference in price was $60, on a camera in the high $300 to low $400 range. Many potential purchasers must have agreed with me, because only 14,310 were produced.
Also lost was the 28 and 35mm viewfinder.
In every other respect, the camera was the same as the SP. It had a single non-rotating speed dial that would couple with the shoe mounted exposure meter. It had the self timer, and the lug for the motor drive. It acquired titanium foil curtains at the same time as the SP. It too, was also available in black finish.
Discontinued in 1961, a batch of 2000 black cameras were sold for the 1964 Olympic games held in Japan. Many of these were fitted with a redesigned 50/1.4 lens that collectors refer to as the "Olympic" 50/1.4.
Serial numbers started at 6300001.
Nikon S3 Olympic, with 50/1.4 Olympic Nikkor
The box for the Nikon S3