GMC 3000 high beam and low beam headlight bulbs utilize H5001, H6024, and H5006 sizes depending on configuration. The replacement chart covers 1960 to 1966 production years with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The GMC 3000 headlight specifications across 1960-1966 reference three sealed beam unit types: H5001, H6024, and H5006. All three conform to ANSI standards recognized in both the United States and Canada, and all operate on 12 volts.
Each of these three unit types is a sealed beam design, meaning the lens, reflector, and filament are fused into a single assembly. When a filament fails, the entire unit is replaced rather than an individual bulb.
The H6024 is a 7-inch round sealed beam unit. It serves as both the high beam and low beam source on GMC 3000 vehicles equipped with a 2-headlamp configuration across 1960-1965, making it a dual-function unit within that setup.
The H5001 is a 4-inch square sealed beam unit designated for the high beam position on GMC 3000 vehicles with a 4-headlamp configuration from 1960-1965, and it is the sole high beam unit specified for 1966 regardless of headlamp count.
The H5006 is a 5.75-inch round sealed beam unit assigned to the low beam position on 4-headlamp configurations of the GMC 3000 from 1960-1965, and it is the sole low beam unit specified for 1966.
The headlamp configuration of the GMC 3000 directly determines which bulb sizes are required. A 2-headlamp setup uses H6024 units for both beams, while a 4-headlamp setup splits the function between H5001 for high beam and H5006 for low beam. Substituting one for the other would reflect an incompatible fitment.
The 1966 GMC 3000 specifications list only H5001 for high beam and H5006 for low beam, with no headlamp count condition noted, distinguishing it from the conditional entries of 1960-1965.