GMC PM151 headlight bulbs utilize H6024 and H6006 sizes for both high beam 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 GMC PM151 uses two distinct sealed beam types across its model years: the H6024 for 1956-1957 and the H6006 for 1955.
Both the H6024 and H6006 are sealed beam units, meaning the lens, reflector, and filament are fused into a single assembly. When the filament fails, the entire unit requires replacement rather than an internal bulb swap.
The H6024 is a 7-inch round sealed beam unit operating at 12 volts, 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 12 volts and built to the same ANSI standard as the H6024.
On the 1956-1957 PM151, the high beam and low beam positions use the same H6024 unit, indicating a dual-function or paired sealed beam configuration rather than separate dedicated bulbs for each function.
The same relationship holds for the 1955 PM151, where both the high beam and low beam positions share the H6006 specification.
The H6024 and H6006 are not interchangeable with each other. Their differing form factors, one round and one rectangular, correspond to different headlight housings and mounting configurations.