The GMC PM250 headlight bulb size specifications include H6024 and H6006 bulb options for both high and low beam applications. The replacement chart covers 1955 through 1957 production years with corresponding bulb size data.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The GMC PM250 uses two distinct sealed beam unit types across its 1955-1957 model years: the H6024 and the H6006, both of which are ANSI-standard units approved for use in the United States and Canada.
The H6024 is a 7-inch round sealed beam unit operating at 12 volts. Because it is a sealed beam design, the entire unit is replaced rather than an internal filament or bulb element.
The H6006 is a 5x7-inch rectangular sealed beam unit, also rated at 12 volts and similarly requiring full unit replacement rather than a component swap.
The 1956-1957 GMC PM250 uses the H6024 for both high beam and low beam headlight positions, meaning a single bulb type serves both functions across those two years.
The 1955 model year is fitted with the H6006 for both the high beam and low beam positions, making it the only year in this range to use the rectangular sealed beam format.
The H6024 and H6006 are not interchangeable. The round and rectangular form factors are physically distinct, and substituting one for the other is not supported by the specifications.