GMC 1500 Series high beam and low beam headlight bulbs utilize H6024, H5001, and H5006 bulb sizes depending on beam type and model configuration. The replacement chart covers 1960 through 1965 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 GMC 1500 Series headlight bulb specifications for 1960-1965 are divided by headlamp system configuration, with two-headlamp vehicles using different bulb sizes than four-headlamp vehicles across both high beam and low beam positions.
The H6024 is a 7-inch round sealed beam unit operating at 12V and conforming to ANSI standards applicable in the US and Canada. It serves as both the high beam and low beam bulb on two-headlamp configurations of the GMC 1500 Series across all listed model years, meaning a single unit type handles both lighting functions in that setup.
All three bulb types used across these specifications, H6024, H5001, and H5006, are sealed beam units. In a sealed beam design, the lens, reflector, and filament are fused into one assembly, so the entire unit is replaced rather than an internal bulb alone.
Four-headlamp configurations split the high beam and low beam functions between two distinct sealed beam sizes. The H5001, a 4-inch square sealed beam unit rated at 12V, handles the high beam position, while the H5006, a 5.75-inch round sealed beam unit also rated at 12V, handles the low beam position.
The H5001 and H5006 are not interchangeable with each other despite both being used in four-headlamp systems. They differ in shape and size, with the H5001 being square and the H5006 being round, which means each occupies a physically distinct housing in the headlamp assembly.
The H6024 and H5006 are both round sealed beam units but are not interchangeable. The H6024 measures 7 inches across while the H5006 measures 5.75 inches, and each is designed for a specific housing in its respective headlamp configuration.
All bulb sizes listed across the specifications operate at 12V, which is consistent with the standard automotive electrical system voltage used in production vehicles of that era.
The headlamp configuration of a specific 1500 Series vehicle, whether two-headlamp or four-headlamp, is the determining factor for which sealed beam sizes are required, and substituting a bulb from the wrong configuration would result in a physical fitment mismatch.