I pulled both lamps from the fixtures, it would seem you are very correct and it seems to be a good way of dating not persay a
fixture but the lamps in them at least. Exact same markings on both the G-40 1Kw
mogul screw
base and 2Kw
mogul screw
base lamps only some of the writing on them is different.
In this case, both have the GE symbol at the center, both have at the bottom of the symbol
Base Down to Horz., on the Mazda lamp it says "Spotlight" first than below it Mazda (probably much to do with a smaller dia. to write it within.) The other 2Kw/120v theorized to be newer lamp has General
Electric, than Spotlight. Same font and size to all lettering otherwise and very similar if not the same to a modern off the shelf 400G40Spot lamp from GE.
So as opposed to the photo industry where you would have a say #1 PhotoFlood, or Fulchs Text reference number to these lamps, we have the Mazda as the better quality standard and one that's standardized for the industry much similar to the
ANSI system or even GE/Thorn's HX
system. Why Mazda for these #26 verses #28 lamps based on the Mazda
system?
Further questions. Given these medium or mog. screw lamps in use, I'm noting that none of the fixtures of that era have reflectors in them. Why is this?
Further question, washing lenses in the dish washer works out really well. How about also doing so with lamps such as these?