Buick Electra Headlight Bulb Size

Additional Notes

• The 9004 is a dual-filament halogen bulb rated at 12V with a 65W high beam filament and a 45W low beam filament, using a P29t base. Because it serves both beam functions within a single unit, the Buick Electra's 1990 model year uses the same 9004 bulb for both the high beam and low beam positions.
• The H5001 and H5006 are sealed beam units conforming to the ANSI standard for the US and Canadian markets. The H5001 is a 4-inch square unit used for the high beam position, while the H5006 is a 5.75-inch round unit used for the low beam position. Both operate at 12V, and neither contains a replaceable bulb; the entire sealed unit is the serviceable component. These types were fitted to the Electra from 1959 through 1975.
• The H4651, H4652, and H4656 are all 4x6-inch rectangular sealed beam units operating at 12V under the ANSI standard. Like the round and square sealed beam types, none of these accept a replaceable internal bulb; the whole unit is replaced upon failure. The H4652 is specifically described as a variant of the H4651.
• The Buick Electra used H4651 for the high beam position across 1976-1986, while the low beam position during that same general period alternated between H4652 and H4656 depending on the specific model year, indicating that the two beam positions used physically distinct sealed beam units throughout the rectangular sealed beam era.
• The low beam sealed beam type for the Electra was not uniform across the rectangular sealed beam years. The H4656 was fitted in 1976-1977, 1979, 1981-1983, and 1986, while the H4652 appeared in 1978, 1980, 1984, and 1985. Substituting one for the other without confirming the correct year-specific fitment would be an error, as they are distinct ANSI part numbers despite sharing the same physical form factor.