Pontiac Grand LeMans Headlight Bulb Size

Additional Notes

• The H6054 is a 5x7-inch rectangular sealed beam unit operating at 12V and conforming to ANSI standards recognized in both the United States and Canada. It serves as both the high beam and low beam headlight on the Pontiac Grand LeMans for model years 1978-1981, meaning a single bulb type covers both functions across those four years.
• All headlight types listed across the Grand LeMans model years are sealed beam units, meaning the entire housing and lens assembly is replaced as one piece rather than a separate replaceable bulb being fitted inside a housing.
• The 1975 Grand LeMans uses the H6024, a 7-inch round sealed beam unit operating at 12V, for both high beam and low beam functions. This round format contrasts with the rectangular sealed beam units used in all subsequent model years covered by these specifications.
• The H4651 and H4652 are both 4x6-inch rectangular sealed beam units operating at 12V under ANSI standards. The H4652 is a variant of the H4651, with the H4651 designated for high beam use and the H4652 for low beam use on the 1976-1977 Grand LeMans. Despite their physical similarity, these two types are not interchangeable between beam positions.
• The shift from 4x6-inch rectangular units in 1976-1977 to 5x7-inch rectangular units in 1978 represents a change in sealed beam size, and the H4651 or H4652 units are not a physical match for housings designed around the larger H6054 format.
• Because the H6054 handles both high and low beam functions in 1978-1981, the Grand LeMans during those years used a dual-function sealed beam system rather than separate dedicated high and low beam units of different types.