GMC K3500 Headlight Bulb Size

Additional Notes

• The GMC K3500 headlight bulb specifications span the 1979-2000 model years, covering both high beam and low beam positions across multiple headlamp system configurations.
• The H6054 is the most frequently listed bulb across the specifications. It is a 5x7-inch rectangular sealed beam unit operating at 12V. As a sealed beam design, the entire unit is replaced rather than an internal filament or capsule, and it carries ANSI standard recognition for the US and Canada markets.
• For the GMC K3500 model years 1992-2000 equipped with halogen capsule headlamps, the high beam position uses the 9005 and the low beam position uses the 9006. These are separate, non-interchangeable single-filament halogen bulbs. The 9005 operates at 65W with a P20d base, while the 9006 operates at 55W with a P22d base. The differing base types physically prevent cross-installation between the two positions.
• The 1988-1991 four-rectangular-headlamp configuration uses the H4701 for high beam and the H4703 for low beam. Both are 7-inch round sealed beam units operating at 12V, and both require full unit replacement rather than bulb replacement.
• The 1983-1986 four-headlamp configurations introduce the H4651 and H4652 for high and low beam positions respectively, both being 4x6-inch rectangular sealed beam units. The 1982 low beam four-headlamp position uses the H4656 instead of the H4652, which is a distinct 4x6-inch rectangular sealed beam unit despite the similar form factor.
• The 1979-1980 two-round-headlamp configuration uses the H6024, a 7-inch round sealed beam unit at 12V, for both high and low beam positions. This unit is physically distinct from the H6054 used in the two-rectangular-headlamp configuration of the same years and is not interchangeable with it.
• All sealed beam types listed in the specifications, including the H6054, H4701, H4703, H4651, H4652, H4656, and H6024, conform to ANSI standards applicable to the US and Canadian markets and operate at 12V.
• The 1991 model year carries the widest range of high beam and low beam options within a single year, with three distinct configurations listed: two-rectangular, four-rectangular, and halogen capsule, each requiring a different bulb type that is not transferable between configurations.