GMC PM153 headlight bulbs utilize H6024 and H6006 sizes for both high and low beam applications. The replacement chart covers 1955 to 1957 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 H6024 and H6006 are both sealed beam units, meaning the lens, reflector, and filament are fused into a single assembly. When the filament fails, the entire unit is replaced rather than an individual bulb.
The H6024 is a 7-inch round sealed beam unit operating at 12V, conforming to ANSI standards recognized in both the United States and Canada.
The H6006 is a 5x7-inch rectangular sealed beam unit, also rated at 12V and built to the same ANSI standard as the H6024.
The GMC PM153 (1957) uses the H6024 sealed beam for both high beam and low beam headlight positions.
The 1955 PM153 uses the H6006 sealed beam in both the high beam and low beam positions, reflecting a rectangular rather than round housing format.
Because the H6024 is round and the H6006 is rectangular, the two units are not interchangeable between the 1955 and 1957 model years due to differences in housing shape and mounting requirements.
Both units share the same 12V operating voltage, which is consistent with standard 12-volt automotive electrical systems of that era.
The ANSI designation on both sealed beam types indicates conformance to a defined photometric and physical standard, ensuring consistent output and fitment within vehicles designed for that specification.