Pontiac Executive front turn signal bulbs measure 1157NA or 1034NA in size, while rear turn signal bulbs measure 1157 in size. The replacement chart covers 1967 through 1970 model 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 these turn signal positions, appearing in all four rear turn signal positions (1967-1970) on the Pontiac Executive.
All three bulb types listed in these specifications, the 1157NA, 1034NA, and 1157, share the same BAY15d bayonet base and dual-filament design operating at 12V with a 21W/5W output rating.
The BAY15d bayonet base is a two-pin offset base, where the two pins are positioned at different heights to ensure correct polarity orientation during installation.
The dual-filament construction in all listed bulbs serves two functions within a single housing: the higher 21W filament activates for the turn signal, while the lower 5W filament serves as a running or parking light.
The 1157NA and 1034NA variants differ from the standard 1157 in that they use natural amber glass, which produces an amber light output without requiring an amber-tinted lens on the vehicle.
The 1034NA is described as a variant of the 1157 and shares its base type and voltage and wattage ratings, though it carries a distinct ANSI designation.
The Pontiac Executive front turn signal used the 1034NA exclusively in 1969, while the 1967, 1968, and 1970 model years all specified the 1157NA for that same position.
Because the 1034NA and 1157NA share the BAY15d base and identical voltage and wattage ratings, their physical and electrical compatibility warrants attention when sourcing replacements, as the distinct ANSI designations indicate they are not formally interchangeable despite their similarities.