I stopped collecting Nikon F-Mount by SN some 25 years ago. You can go crazy with it, so many lenses and bodies. I got the Rangefinder itch, and the last set that I put together are the Collapsible 5cm F2, 5cm F1.5, 3.5cm F3.5, 8.5cm F2, 13.5cm F4, and Variframe finder, all Leica mount with 1949 Batch numbers on them. The name ring of the collapsible 5cm F2 has a 1948 batch, but the focus mount shows a 1949 batch- one of the few Nikon lenses with separate SN's on the lens and mount. Zeiss did this with the wartime Sonnars, but you had to disassemble the mount to find them.