Lionel used 15 different types of light bulbs in its O gauge electric trains in the postwar era, but in most cases–87% of catalog numbers, and a lot more than that in actual number of items produced–you can get by with two. Since knowing when can be difficult, here’s a Lionel train light bulb chart.
Lionel almost always specified 14 or 18 volts. Using an 18-volt bulb in place of a 14-volt original, or a 22-volt bulb in place of an 18-volt original results in longer service life. And there were two base types that Lionel used more than any other. Read more