Chevrolet Bel Air Brake Bulb Size

The Chevrolet Bel Air brake component utilizes bulb sizes 1157, 1034, and 1154 depending on the specific production period for the vehicle. Available data covers the range from 1950 through 1975 for the specified lighting equipment.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Bulb Size by Year Range

Years	Bulb Size
1964-1975	1157
1955-1963	1034
1950-1954	1154

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base. 12V, 21W/5W.	1157
ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base. Variant of 1157. 12V, 21/5W.	1034
ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base. Older variant of 1157. 6V/12V.	1154

Other Locations

Additional Notes

The brake bulb specifications for the Chevrolet Bel Air span the 1950-1975 model years and reference three distinct ANSI-standard bulb types: the 1157, the 1034, and the 1154.
The 1157 is the most widely specified bulb across the Bel Air lineup, covering the 1964-1975 model years. It is a dual-filament bulb with a BAY15d bayonet base, rated at 12V with a 21W/5W filament output, where the higher wattage serves the brake function and the lower wattage serves a secondary circuit.
The BAY15d bayonet base is a two-pin offset base design. The offset pin placement is a deliberate fitment feature that ensures the bulb is inserted in only one rotational orientation, which is critical for dual-filament applications where each filament must align with its corresponding circuit contact.
The 1034 is specified for the Chevrolet Bel Air across the 1955-1963 model years. It shares the same BAY15d bayonet base and 12V/21W/5W electrical ratings as the 1157 and is classified as a variant of that bulb type.
The 1154 is specified for the 1950-1954 model years. It is described as an older variant of the 1157 and carries a dual-voltage rating of 6V/12V, which reflects the transition-era electrical systems of that period, as many vehicles of that time used 6-volt rather than 12-volt systems.
Although the 1034 and 1157 share the same base type and wattage ratings, they are distinct ANSI part numbers. Substitution between them warrants verification against the specific model year, as variant designations within the ANSI system can reflect differences in filament geometry or base tolerances.
The 1154 is not rated exclusively for 12V operation, unlike the 1034 and 1157. Installing a 6V-rated bulb in a 12V system, or vice versa, produces incorrect light output and can shorten bulb life or cause circuit issues.