SOLD on Pellican
NOS Aluminum ST/RSR NOS Blau oil cap, also used on several other Porsche (race) cars. The caps are 86mm outside diameter and have a cork seal.
It comes with a 1.5 inch fillerneck so you can fab your own ST/RSR filler mouth on your oil tank. (These necks are 80 mm outside diameter)
Photos soon
$150 shipped CUSA