For reasons I don't know the history of, some '60's Fairladys and other roadsters came with a "griffin" on the key from the factory. If I recall, some also had it on the floor mats. The Griffin of mythology had the body of a lion with the head and wings of an eagle, so I'm not sure where the derivation comes from. To me the one on the key looks like a lion. However, the griffin does appear in some Central Asian mythology in similar form, so I suppose a Japanese car company adopting it isn't entirely inappropriate. AZ may know more about the "Nissan Griffin" history than I do.
There's an outfit in Washington State called Rallye Enterprises selling what seem to be nice reproductions, but I don't know much about them or if they sell them just for Fairladys or in all the various key-cylinder configurations used in early Nissans:
http://www.datsunroadster.com/PIC_PAGES ... y_info.htm