The Buick Centurion front turn signal requires either a 1157NA or 1034NA bulb size, while the rear turn signal uses a 1157 bulb size. The replacement chart covers 1971 through 1973 production years with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Buick Centurion turn signal specifications cover the 1971-1973 model years, spanning both front and rear positions.
All three bulb types listed across these specifications, the 1157NA, 1034NA, and 1157, share the BAY15d bayonet base and a dual-filament design operating at 12V with a 21W/5W output rating.
The BAY15d base is a double-contact bayonet fitting with offset pins, a design that prevents incorrect installation by ensuring the bulb can only be seated in one orientation.
The dual-filament construction in all three bulb types allows a single bulb to serve two functions, typically combining a brighter filament for the turn signal flash with a dimmer filament for a running or parking light.
The 1034NA is described as a variant of the 1157, meaning the two share closely related electrical and physical characteristics despite carrying different ANSI designations.
The "NA" suffix on the 1157NA and 1034NA designations indicates natural amber glass, which produces an amber signal output without requiring an amber lens or a separate colored coating.
The Buick Centurion front turn signal changed from the 1034NA in 1971-1972 to the 1157NA in 1973, representing a shift between two related but distinct bulb designations at that position.
The rear turn signal used the 1157 across all three model years, 1971-1973, with no variation in bulb designation over that period.
The 1157 used at the rear position lacks the "NA" suffix, indicating it has a clear glass envelope rather than natural amber glass, which means amber coloring at that position would depend on the lens rather than the bulb itself.
Because the 1034NA and 1157NA both share the BAY15d base and identical 12V/21W/5W ratings, physical fitment at the socket level is the same, though the variant designation of the 1034NA suggests there may be minor differences that affect direct interchangeability.