GMC G25 high beam and low beam headlight bulbs utilize H6024 and H5001 sizes for high beams, along with H6024 and H5006 sizes for low beams in this truck model. The replacement chart covers 1967 to 1978 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 G25 headlight bulb specifications span the 1967-1978 model years, covering both high beam and low beam positions across two distinct sealed beam generations.
The H6024 is a 7-inch round sealed beam unit operating at 12V and conforming to ANSI standards recognized in both the United States and Canada. On the GMC G25, it serves as both the high beam and low beam headlight for the 1973-1978 model years, meaning a single bulb type covers both functions in those years.
Sealed beam units such as the H6024, H5001, and H5006 are not serviceable in the conventional sense. When a sealed beam fails, the entire unit requires replacement rather than an internal bulb swap.
The H5001 is a 4-inch square sealed beam unit operating at 12V under ANSI standards. It fills the high beam position on the GMC G25 for the 1967-1972 model years.
The H5006 is a 5.75-inch round sealed beam unit operating at 12V under ANSI standards. It fills the low beam position on the GMC G25 for the 1967-1972 model years.
The 1967-1972 model years use two different sealed beam types simultaneously, with the H5001 handling high beam duties and the H5006 handling low beam duties. These two units are not interchangeable with each other due to their differing physical sizes and beam functions.
The shift from the H5001 and H5006 pairing to the single H6024 type occurred between the 1972 and 1973 model years, reflecting a change in headlight configuration for the G25.
Although the H6024 and H5006 are both round sealed beam units, their differing sizes of 7 inches and 5.75 inches respectively make them physically incompatible with each other's housings.