The Buick GS uses an H5001 bulb size for high beam headlights and an H5006 bulb size for low beam headlights. The replacement chart covers 1970 through 1972 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 Buick GS uses two distinct sealed beam types across its 1970-1972 model years: the H5001 for high beam and the H5006 for low beam.
Both the H5001 and H5006 are sealed beam units, meaning the lens, reflector, and filament are fused into a single assembly. When a filament fails, the entire unit is replaced rather than an internal bulb.
The H5001 is a 4-inch square sealed beam unit operating at 12V, conforming to ANSI standards recognized in both the United States and Canada.
The H5006 is a 5.75-inch round sealed beam unit, also rated at 12V and built to the same ANSI standard applicable in the United States and Canada.
The square profile of the H5001 and the round profile of the H5006 reflect a common practice in this era of using physically distinct housings for high and low beam functions, which prevents cross-installation between the two positions.
The H5001 high beam specification remains consistent across all three model years (1970-1972) of the Buick GS covered in these specifications, indicating no mid-cycle change to that lighting position.
The H5006 low beam specification is likewise unchanged across the 1970-1972 range, confirming that both lighting positions held the same bulb fitment throughout this period.