The International R121 high beam and low beam headlight bulbs both utilize the H6024 bulb size. The replacement chart covers vehicle production spanning 1953 to 1955.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The H6024 is a 7-inch round sealed beam unit operating at 12 volts, built to ANSI standards recognized in both the United States and Canada.
Unlike bulb-and-housing systems, the H6024 is a self-contained unit in which the filament, reflector, and lens are fused together, meaning the entire assembly is replaced rather than an individual bulb.
The International R121 uses the H6024 for both high beam and low beam headlight positions across the 1953-1955 model years.
Because the same H6024 unit serves both beam functions, the R121 does not use separate bulb types to distinguish between high and low beam output.
The ANSI designation on the H6024 indicates the unit conforms to standardized dimensional and photometric requirements, which historically allowed sealed beam units of the same type to be interchangeable across different vehicle makes and models sharing that specification.