Chevrolet C70 Headlight Bulb Size

Additional Notes

• The Chevrolet C70 headlight system is configured in one of two ways depending on the vehicle: a two-headlamp setup or a four-headlamp setup. Each configuration uses a distinct set of sealed beam bulb sizes, and the correct replacement unit depends entirely on which headlamp count the vehicle carries.
• The H6024 is a 7-inch round sealed beam unit conforming to ANSI standards for the US and Canadian markets. It operates at 12V and serves as both the high beam and low beam in two-headlamp configurations, meaning a single unit type handles both functions on that setup.
• The H4651 and H4656 are both 4x6-inch rectangular sealed beam units operating at 12V under ANSI standards. In four-headlamp configurations, the H4651 is designated for high beam duty while the H4656 handles low beam duty, making the two non-interchangeable despite sharing the same physical form factor.
• The H6054 is a 5x7-inch rectangular sealed beam unit, also rated at 12V and conforming to ANSI standards. It appears exclusively in the 1984 model year for two-headlamp configurations in both the high beam and low beam positions, distinguishing 1984 from surrounding years that use the H6024 in the same configuration.
• All four bulb types listed are sealed beam units, meaning the lens, reflector, and filament are fused into a single assembly. When a filament fails, the entire unit requires replacement rather than just an internal bulb.
• In two-headlamp configurations, the H6024 covers 1960-1961 and 1979-1990 across both high and low beam positions, with 1984 being the sole exception where the H6054 is specified instead.
• The 1989 and 1990 four-headlamp low beam entries do not list an H4656, whereas the high beam entries for those years retain the H4651, reflecting a difference in specification between the two beam positions for that period.
• Because the H4651 and H4656 share the same 4x6-inch rectangular housing, substituting one for the other would place an incorrectly aimed beam pattern in service, as each unit is optically engineered for its designated beam function.