GMC C3500 Headlight Bulb Size

Additional Notes

• 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 headlight across the GMC C3500 from 1979 through 2000 in configurations equipped with sealed beam or two-headlamp systems. As a sealed beam unit, the entire assembly is replaced rather than an internal bulb.
• The 9005 and 9006 are single-filament halogen capsule bulbs used in the GMC C3500 from 1988 through 2000 when the vehicle is equipped with halogen capsule headlamps. The 9005 handles the high beam function at 12V and 65W with a P20d base, while the 9006 handles the low beam function at 12V and 55W with a P22d base. Despite their similar appearance, the two types use different base designs and are not interchangeable.
• The H4701 and H4703 are 7-inch round sealed beam units used on the GMC C3500 from 1988 through 1991 in four-rectangular-headlamp configurations. The H4701 is designated for the high beam position and the H4703 for the low beam position. Both are complete assemblies replaced as a whole unit.
• The H4651 and H4656 are 4x6-inch rectangular sealed beam units used in four-headlamp configurations on the C3500 from 1982 through 1986. The H4651 covers the high beam position and the H4656 covers the low beam position across most of those years, with the H4652, a variant of the H4651, appearing in the low beam position specifically for the 1984 model year.
• The H6024 is a 7-inch round sealed beam unit operating at 12V, used on the GMC C3500 in 1979 and 1980 when the vehicle is equipped with two round headlamps. It covers both the high beam and low beam positions in that configuration and, like all sealed beam types in these specifications, is replaced as a complete unit.
• The GMC C3500 from 1988 through 1991 supported three distinct headlamp system configurations simultaneously: two rectangular headlamps, four rectangular headlamps, and halogen capsule headlamps. Each configuration requires a different set of bulb types, making the headlamp system type a critical factor in determining the correct fitment.
• All sealed beam units listed across these specifications, including the H6054, H4701, H4703, H4651, H4652, H4656, and H6024, conform to ANSI standards applicable in the US and Canada. None of these units contain a serviceable internal bulb; the sealed beam housing and light source form a single integrated component.
• The 1984 GMC C3500 with four headlamps uses the H4652 for the low beam position rather than the H4656 used in surrounding years. The H4652 is a variant of the H4651 and shares the same 4x6-inch rectangular sealed beam format, but the two are not listed as equivalent in these specifications.