NIKKOR 50mm 1:1.4 (ais) – 5496331 – 1994
NIKKOR 50mm 1:1.4 (ai) – 4491668 – 1980
NIKKOR-S Auto 1:1.4 f=50mm – 554600 – 1967
http://www.photosynthesis.co.nz/nikon/lenses.html#50
specs (pdf)
Nikon 50mm f1.4 AI lens test on Canon 5D Mk II
Nikon 50mm f/1.4 Ai Disassembly and Cleaning