This is a nissan/datsun oil cap from the 70's, however I am not sure on what cars this particular cap was provided on. Anybody know? (What car?) (what country?) It looks a little like a 280ZX cap but I think its a little different.

Never seen one like that. We did a thread on oil caps maybe about a year ago. You know, the two 'elephant' caps, the one that just says 'OIL' that some call the '710' cap, etc. Actually, it looks like the basic run-of-the-mill cap that someone has removed the kanji characters from somehow.