I've been busy trying to keep records for three different bridge rehab projects, disect a 30 page legal document by a contractor demanding the client pay them an extra $1.5 million and teaching one of my inspectors how to fill out his time sheet again this week. But in my spare time I do have two mechanical wrist watches being checked for accuracy. So far the 61 year old one is running about 2x more accurate than the 2 year old one.
Anyway.....
The military spec'd certain items to be able to do X, Y or Z in certain conditions. Regarding flashlights if I recall correct they didn't spec a certain brand. They would put out an invitation for bids and companies would respond with a light they thought could pass the requirements. Companies like Bright Star, Delta electric, Fulton and Stewart Brown, US Lite and others built them.
Fulton was able to muster up enough product where they supplied the most lights. For whatever reason the largest manufacturer (Eveready) did not make many kights for the military back then.
Certain sectors of armed forces spec'd some specifics for specific duties. Navy pilot map readers for example had a dome lens to spread light from a 2D flashlight. Some were plastic, some were metal. But they needed a nail hook and a screw off dome lens in order to become a normal beam flashlight and change a bulb in the dark.
The foot soldiers be it Army or Marines had a right angle head 2D flashlight. They added an extra bulb holder to the requirements then later colored filters (TL122 A, B, C and D, which became the MX/990 for Korea on) Fulton, US Lite, GT Price, and others built those.
The Coast Guard spec'd 3D flashlights that could float when empty. Bright Star built a lot of those. Some used below deck were required to be intrinsicaly safe. Stewart Brown built a bunch of those out of anti-static bake-a-lite vs typical plastics that could generate static electricity.
I would surmize a mechanic light would have been a dull black plastic straight head with an antiroll shaping. Perhaps a spare bulb in the tailcap much like the one
@RWT1405 showed in post 5 but maybe not required to do morse code.
Maybe check out getalite.net for info or links to other sites that may help. If that doesn't work email the site owner David White.