Chevrolet Vega front turn signal bulbs utilize 1157, 1157NA, or 1034NA bulb sizes, while rear turn signal bulbs use 1157 size. The replacement chart covers 1971 through 1977 production years with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 1157 bulb is the most frequently specified type across the Chevrolet Vega's turn signal positions, appearing in the rear turn signal for all model years from 1971-1977 and in the front turn signal for 1971, 1974, 1975, and 1977.
The 1157 is a dual-filament bulb rated at 12V with a 21W high filament and a 5W low filament, mounted on a BAY15d bayonet base, which allows it to serve both turn signal and parking light functions within a single housing.
The BAY15d bayonet base uses two offset pins to ensure correct orientation during installation, a design that prevents the filaments from being wired to the wrong circuit.
The 1157NA, specified for the Chevrolet Vega front turn signal in 1972 and 1976, shares the same 12V, 21W/5W dual-filament construction and BAY15d base as the standard 1157 but is distinguished by natural amber glass rather than a clear envelope.
The natural amber glass of the 1157NA produces an amber output directly from the bulb itself, which means the amber color does not depend on a tinted lens to meet turn signal visibility requirements.
The 1034NA, specified for the front turn signal in 1973, is described as a variant of the 1157 and carries the same 12V, 21W/5W ratings and BAY15d base, along with natural amber glass.
Despite the functional and physical similarities among the 1157, 1157NA, and 1034NA, they carry distinct ANSI designations, and substituting one for another may affect whether the amber color requirement is met by the bulb or must instead be provided by the lens.
All three bulb types in these specifications conform to ANSI standards recognized in both the United States and Canada, indicating compliance with North American automotive lighting regulations.