The Buick Invicta high beam headlight uses an H5001 bulb size while the low beam headlight requires an H5006 bulb size. The replacement chart covers vehicle production years spanning 1959 to 1963 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 Buick Invicta uses the H5001 bulb for high beam headlights and the H5006 bulb for low beam headlights across all model years from 1959-1963.
Both the H5001 and H5006 are 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 swap.
The H5001 is a 4-inch square sealed beam unit operating at 12 volts and 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 12 volts and built to the same ANSI standard applicable in the United States and Canada.
The physical shape difference between the two units is a direct fitment factor. The square H5001 and the round H5006 occupy distinct housings and are not interchangeable with each other.
The consistent use of H5001 and H5006 across all five model years of the Buick Invicta indicates that replacement units sourced for any year within the 1959-1963 range share the same specifications.