GMC C2500 Suburban Headlight Bulb Size

Additional Notes

• The GMC C2500 Suburban uses two distinct headlamp system types across its model years: sealed beam units, which are self-contained glass assemblies replaced as a whole, and halogen capsule systems, which use small replaceable bulbs housed within a separate reflector assembly.
• The H6054 is a 5x7-inch rectangular sealed beam unit operating at 12V and conforming to ANSI standards for the US and Canadian markets. It serves as both the high beam and low beam source in sealed beam configurations across the 1981-1999 model years of this vehicle.
• For 1992-1999 models equipped with halogen capsule headlamps, the high beam and low beam functions are handled by separate bulbs. The 9005 handles high beam duty at 65W, while the 9006 handles low beam duty at 55W. Both operate at 12V and use single-filament designs, though they have different bases, the P20d and P22d respectively, making them non-interchangeable despite their similar appearance.
• The H4651, H4652, and H4656 are all 4x6-inch rectangular sealed beam units used in four-headlamp configurations on 1982-1986 models. H4652 is a variant of H4651. In the four-lamp arrangement, H4651 covers high beam and H4656 or H4652 covers low beam, depending on the model year.
• The H6024 is a 7-inch round sealed beam unit operating at 12V, used on the 1979-1980 model years. Like all sealed beam types in these specifications, the entire unit is replaced rather than an internal bulb.
• Fitment between the sealed beam and halogen capsule bulb types is not interchangeable, as each system requires a different housing design. On 1992-1999 models, the correct bulb type depends strictly on which headlamp system the vehicle was built with.
• The low beam sealed beam bulbs used in four-headlamp configurations differ between certain model years. The 1985 model uses H4652 for low beam, while 1982-1983 and 1986 models use H4656, making year-specific verification necessary for four-lamp equipped vehicles.
• All bulb types listed across these specifications conform to ANSI standards applicable in both the United States and Canada, indicating a shared regulatory framework governing their physical and electrical characteristics in those markets.