The Buick GS 350 headlight bulb specifications include an H5001 size for high beam operation and an H5006 size for low beam operation. The replacement chart covers 1968 to 1969 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 H5001 and H5006 bulb types listed for the Buick GS 350 are both sealed beam units, meaning the lens, reflector, and filament are fused into a single housing. When the filament fails, the entire unit requires replacement rather than an internal bulb.
The H5001 is a 4-inch square sealed beam unit conforming to ANSI standards recognized in both the United States and Canada. It operates on a 12-volt system and serves the high beam function on the GS 350 across the 1968-1969 model years.
The H5006 is a 5.75-inch round sealed beam unit, also ANSI-standardized for the US and Canadian markets. It operates on 12 volts and fills the low beam role across the same 1968-1969 model years.
Because both units are sealed beams governed by ANSI dimensional and photometric standards, physically compatible replacements from different manufacturers are generally interchangeable, provided the correct type designation is matched.
The H5001 and H5006 are distinct unit types and are not interchangeable with each other. The square format of the H5001 and the round format of the H5006 correspond to separate housing cavities within the headlight assembly, each serving a dedicated beam function.