Oil fill cap for Series 2 (2.25L)

[SK Rover]

I somehow lost the cap for the oil fill on my Series 2. Does anyone know if there is something at NAPA or elsewhere that would fit. Looks pretty standard but the guys that work there seem to need a part # to look up and unfortunately a 1959 Land Rover is not in their system.

Any help would be appreciated.

[SK Rover]

The screw on style