GMC Topkick high beam and low beam headlight bulbs both utilize the H6054 bulb size. The replacement chart covers vehicle production spanning 1990 to 2009.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The GMC Topkick uses the H6054 bulb size for both high beam and low beam headlights across all model years from 1990 to 2009.
The H6054 is a 5x7-inch rectangular sealed beam unit, meaning the lens, reflector, and filament are fused into a single assembly rather than a separate bulb housed within a reflector housing.
Because the H6054 is a sealed beam unit, the entire assembly is replaced when the light fails, rather than swapping out an individual bulb.
The H6054 operates at 12 volts and conforms to ANSI standards recognized in both the United States and Canada.
The identical H6054 specification for both the high beam and low beam positions indicates that the GMC Topkick uses a dual-filament sealed beam arrangement, where a single unit serves both lighting functions.
The H6054 designation is a standardized size code, which means units from different manufacturers sharing that designation are generally interchangeable as long as they meet the same ANSI specification.