The White/GMC WHEB high beam and low beam headlight bulbs use a 9004 or H6024 bulb size. The replacement chart covers 1991 to 1995 production years with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The White/GMC WHEB used two distinct headlamp systems across the 1991-1995 model years: composite headlamps and sealed beam headlamps. Each system requires a different bulb type, and the two are not interchangeable.
The 9004 is a dual-filament halogen bulb operating at 12V with a wattage rating of 65W on the high beam filament and 45W on the low beam filament. Its P29t base is a proprietary connector format specific to this bulb family.
Because the 9004 contains two filaments within a single housing, it serves both the high beam and low beam functions in composite headlamp-equipped WHEB units. A single bulb replacement addresses both lighting modes.
The H6024 is a 7-inch round sealed beam unit conforming to ANSI standards recognized in both the United States and Canada. Unlike the 9004, the H6024 is not a replaceable bulb; the entire sealed unit is replaced as one assembly.
Both the 9004 and H6024 are ANSI-standardized types, meaning they are produced by multiple manufacturers to a common specification rather than being proprietary to a single supplier.
The H6024 sealed beam unit handles both high and low beam output within the same assembly, which is consistent with its role as a direct counterpart to the dual-filament 9004 in the sealed beam configuration.
The headlamp system fitted to a given WHEB unit determines which bulb type applies. Substituting a 9004 into a sealed beam housing or an H6024 into a composite housing is not supported by these specifications.