I have a handful of incandescent bayonet type toy train bulbs. Some are clearly labeled, 14v, 12-16v, 18v, others are not. Is there a way to ID bulb voltage by resistance? The labeled ones are fairly consistent in resistance. The one I am looking to replace has a higher resistance (32Ω) but are not labeled. I'm guessing these are rated for above 18v, as they are much dimmer than the 18v bulbs at 18v. These were installed in K-Line Heavyweights that I picked up, which had 2 different bulbs in one car.