The GMC G15 high beam headlight uses H6024 or H5001 bulb sizes, while low beam headlight applications require H6024 or H5006 bulb sizes for this model. The replacement chart covers vehicle production years spanning 1967 to 1978 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 G15 headlight specifications cover the 1967-1978 model years, with two distinct bulb configurations used across that span depending on the model year.
The H6024 is a 7-inch round sealed beam unit operating at 12V and conforming to ANSI standards for the US and Canada. It serves as both the high beam and low beam headlight on the GMC G15 for the 1973-1978 model years, meaning a single bulb type covers both functions in a dual-beam arrangement.
The H5001 is a 4-inch square sealed beam unit operating at 12V and conforming to the same ANSI standards. It functions as the high beam headlight on the G15 for the 1967-1972 model years.
The H5006 is a 5.75-inch round sealed beam unit operating at 12V under the same ANSI designation. It serves as the low beam headlight on the G15 for the 1967-1972 model years, pairing with the H5001 in a four-headlight system where high and low beams are handled by separate units.
All three bulb types are sealed beam units, meaning the lens, reflector, and filament are fused into a single assembly. Replacement requires swapping the entire unit rather than an internal bulb.
The H5001 and H5006 are not interchangeable with each other despite both being used in the same model years. Their physical form factors differ, and each is assigned to a specific beam function.
The H6024 used on 1973-1978 models is also not interchangeable with the H5001 or H5006 units from earlier years, as it differs in both physical size and beam function consolidation.
Because all three types follow ANSI standards, replacement units from any ANSI-compliant manufacturer are electrically and physically compatible with the original equipment, provided the correct type designation is matched.