The most reasonably priced component used on the T500 1971 1972 1973 1974 1975 (r) (j) (k) (l) (m) Usa (e03) Frame - Oil Tank is the O Ring(d:3,id:23).
In this schematic the "Bolt" is used most often.
A sample from the products for the Frame - Oil Tank include: Hose(5x8x2000), Gasket,oil Tank Filler Cap (nas), Screw, Nut.