The GMC 2500 Series headlight bulb specifications include H6024 and H5001 sizes for high beam applications, along with H6024 and H5006 sizes for low beam functions. The replacement chart covers 1960 to 1965 model years with corresponding bulb size data.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The GMC 2500 Series from 1960-1965 used three sealed beam bulb types across its headlamp configurations: H6024, H5001, and H5006. All three are ANSI-standardized units rated at 12V and sold in the US and Canadian markets.
Sealed beam units house the filament, reflector, and lens in a single fused glass assembly. When a sealed beam fails, the entire unit is replaced rather than an internal bulb.
The H6024 is a 7-inch round sealed beam that served as both the high beam and low beam unit in 2-headlamp configurations across all six model years covered in the specifications.
The GMC 2500 Series with 4-headlamp configurations used two distinct sealed beam types split by function: the H5001, a 4-inch square unit, handled high beam duty, while the H5006, a 5.75-inch round unit, handled low beam duty.
The H6024 and H5006 differ in physical form despite both being round sealed beams. The H6024 measures 7 inches and handles both beam functions in a 2-lamp system, whereas the H5006 measures 5.75 inches and is dedicated solely to low beam output in a 4-lamp system.
The H5001 is the only square-format sealed beam in these specifications. Its 4-inch square form factor is not interchangeable with the round H6024 or H5006 units, as the mounting hardware and housing geometry differ between round and square sealed beam designs.
In 4-headlamp systems, the high beam and low beam positions use physically different sealed beam sizes and shapes. Swapping the H5001 and H5006 between positions would result in incorrect fitment due to the difference between square and round housings.
The headlamp configuration of a given vehicle, either 2-headlamp or 4-headlamp, determines which bulb types apply. A 2-headlamp vehicle uses only the H6024, while a 4-headlamp vehicle requires both the H5001 and H5006.