According to Olive Drab .com:
The WW2 right angle light started out as a TL122, then a A model, then a B, and C. The D model was where the spare lenses began. Red, blue and a spare clear. And yes they were for signaling or just putting out a lot less light. Red makes it really dim where blue dims but makes map reading with red markings easier to read.
It may be that you guys had the next generation of right angled military lights.. the MX 91 or 991U. They had blue, green, anmber, red, blackout and diffuser. Blackout being the white lens. Diffuser was textured.
You can still acquire the lens kit at Fulton. It comes with gaskets and lenses and a new bulb.
You can also acquire an LED upgrade kit from Fulton, which includes a real nice PR based emitter and some D to AA adapters.