Plymouth Custom high beam headlight bulbs measure H5001 in size, while low beam headlight bulbs measure H5006 in size. The replacement chart covers 1958 to 1961 vehicle production years with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Plymouth Custom uses the H5001 sealed beam unit for high beam headlights across the 1958-1961 model years.
The H5001 is a 4-inch square sealed beam unit operating at 12V. It conforms to ANSI standards recognized in both the United States and Canada.
The H5001 is not a replaceable bulb in the conventional sense. When the unit fails, the entire sealed beam assembly is replaced rather than an internal filament or capsule.
Low beam headlights on the Plymouth Custom (1958-1961) use the H5006 sealed beam unit, which is a 5.75-inch round format also rated at 12V and conforming to the same ANSI standard.
Like the H5001, the H5006 is a sealed beam unit requiring full assembly replacement upon failure.
The H5001 and H5006 are physically distinct units. The square profile of the H5001 and the round profile of the H5006 make the two non-interchangeable, as each occupies a different housing position within the headlight assembly.