Chevrolet Parkwood high beam headlight bulbs use H5001 size while low beam headlight bulbs use H5006 size. The replacement chart covers 1959 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 Chevrolet Parkwood used two distinct sealed beam headlight units across its 1959-1961 model years: the H5001 for high beam and the H5006 for low beam.
Both the H5001 and H5006 are sealed beam units, meaning the lens, reflector, and filament are fused into a single assembly. When a filament fails, the entire unit requires replacement rather than an internal bulb swap.
The H5001 is a 4-inch square sealed beam unit operating at 12 volts and conforming to ANSI standards recognized in both the United States and Canada.
The H5006 is a 5.75-inch round sealed beam unit, also rated at 12 volts and built to the same ANSI standard applicable in the United States and Canada.
The square profile of the H5001 and the round profile of the H5006 make the two units physically incompatible with each other's housings, so the high beam and low beam positions are not interchangeable.
The H5001 and H5006 designations follow the ANSI sealed beam nomenclature system, which standardized headlight sizes and electrical ratings to allow cross-manufacturer fitment within the same specification class.