GMC C35 headlight bulbs utilize H6024 and H5001 sizes for high beam applications, with H6024 and H5006 sizes for low beam configurations, representing the bulb specifications across multiple production generations. The replacement chart covers 1967 through 1978 model 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 C35 uses two distinct sealed beam generations across its 1967-1978 model range. The 1967-1972 model years use H5001 and H5006 sealed beams, while the 1973-1978 model years use the H6024 sealed beam for both high and low beam positions.
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. It serves as both the high beam and low beam unit on the GMC C35 for the 1973-1978 model years, meaning a single bulb type covers both functions in that era.
The H5001 is a 4-inch square sealed beam unit operating at 12V under the same ANSI standard. On the GMC C35, it fills the high beam position for the 1967-1972 model years.
The H5006 is a 5.75-inch round sealed beam unit operating at 12V. It occupies the low beam position for the 1967-1972 model years, making it a distinct unit from the H5001 high beam used in the same vehicles during that period.
All three bulb types, H6024, H5001, and H5006, are sealed beam units. In a sealed beam design, the reflector, lens, and filament are fused into a single glass assembly, so the entire unit is replaced rather than an internal bulb alone.
The 1967-1972 configuration requires two different sealed beam part numbers, H5001 for high beam and H5006 for low beam, whereas the 1973-1978 configuration uses a single part number, H6024, across both beam positions. Substituting one for the other across these two eras is not supported by the specifications.
The H5001 and H5006 differ not only in size but also in shape. The H5001 is square while the H5006 is round, which means the two units are physically non-interchangeable despite both appearing in the same vehicle years.
All sealed beam units listed for the GMC C35 operate on a 12V electrical system and meet ANSI standards applicable in both the United States and Canada, indicating cross-border fitment compatibility within those markets.