Triumph 500 Pre-Unit Oil Tank Cap, as NOS, E370A 70-0370 5T

This auction is for ONE cap.  I have a small handful of them, and the second one is shown only to illustrate the cap's underside.

Head diameter of the cap is 2" , thread od is a hair over 1.60".  I believe it is suitable for the very earliest Triumph twins and most pre-unit singles.  It has an early engine-style part number so it must have been used this way in some fashion, as well as for the oil tank.  Finish is Old English polishey nice.