Cowan’s East African Safari 1600 Lancer built by Ralliart was the only Japanese factory rally car I spent any time in during the mid/late 70s.

That was Butler/Twin master fit with white light bulbs.

Since you say the lamp is blue/green source it would suggest a lighting system compatible with early NVG (white light saturates the optics). Most US surplus gear of the Vietnam era would not have been NVG compatible.

1970s US rather than Japanese would be more common on lighting fits of that time but the combination of high tech (for that era) NVG compatible lighting with tripmaster rather than the higher spec twin master is odd.

Although the shade is similar to Type C (yes – standard or cut to suit options) I think a US rather than RAF original source.

Regards
Ross