Fits
the 172-10 cap shown on the website and some other
versions if the gasket looks like this and has an
outer diameter of 2 3/8" and an inner diameter of 1
5/16". The 172-10 cap was original equipment on
67.5-70 cars but could be or not be found on any of
the cars after 45-50 years.
Datsun
Roadster Gas Cap Seal
SPL311
SRL311 Gas Cap Seal from Rallye Roadster