So, as soon as the other six can be found, I own three or more lot numbers or brands of plano convex box spot. This by way of many brands and even yoke verses stand mount. One even with an interesting Fresnel lens I have never seen before. Front side a Fresnel, rear side as if a wide flood PAR 64 lamp in surface. Anyway, these fixtures normally suited for a 400G-FL lamp, I"m modifying for a 20w/12v Ushio BAB/FG lamp Not my optimum choice in shooting for a 45 degree angle and this only giving me 36 degree, but it should still focus sufficiently as a theory. If a 36 degree instead of 40 degree lamp is not sufficient, I still have lots of at least 40 degree choices. This before I move up to the BAB/60 series of 60 degree lamp type but having potentially lots of spill. Anyway, as above, the 1920's fixtures have had their medium screw bases removed and Gimbal mount MR-16 lamps installed in their places. These jacked up to the bench focus height and centered upon the filament as necessary. Kind of cool project - this similar to what I often do with large wattage Fresnels in making them LED or much less wattage fixtures, except in this case they are for my living room. I want low voltage MR-16 in washing the ceiling. Anyway, below is the first two fixtures wired. First set of photos is for the Fresnel version that was stand mounted an Fresnel lensed. Still in all ways a box spot but definately much older by way of very unique lamp base no longer sold and in all other ways just seemingly older. The next set of pootos is the version I have four of all the same and I estimate from the 1940's thru 1950's. Possibly earlier but just got that feeling they are not as old. Some bench focusing to do but it in theory should work. Than again they might not work. Will a MR-16 lamp optimized for focus on a 4.1/2" lens, both Fresnel and PC provide a similar light to that of the 400w flood lamp the fixture was designed about? What will a MR-16 behind a 4.5x6.5 PC lens, and a unique fresnel lens do? Have not plugged them in yet. Given nobody else has ever done such a thing, before I post the answers, let's get some theories here.