The Pontiac Grandville front turn signal requires bulb sizes 1157NA, 1157, or 1034NA, while the rear turn signal uses a 1157 size bulb. The replacement chart covers 1971 through 1975 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 front and rear turn signals across all listed years of the Pontiac Grandville operate on a 12V electrical system, with dual-filament bulbs rated at 21W for the high-intensity filament and 5W for the low-intensity filament.
All three bulb types specified for the Grandville, the 1157NA, 1157, and 1034NA, share the BAY15d bayonet base, a two-pin offset base design that physically locks the bulb into the socket at a fixed rotational position.
The rear turn signal position uses the 1157 across all five model years from 1971-1975, making it the most consistently specified bulb in these listings.
The 1157NA differs from the standard 1157 in that its glass envelope is tinted natural amber, which produces an amber signal output without relying on a colored lens or housing.
The 1034NA is described as a variant of the 1157 and shares the same BAY15d base, 12V rating, and 21W/5W filament configuration, while also featuring natural amber glass.
The front turn signal position on the 1971 Pontiac Grandville uses the 1034NA rather than the 1157NA found in 1972, 1974, and 1975, meaning these two positions are not interchangeable despite the shared base type.
The 1973 front turn signal is specified as a standard 1157, which lacks the natural amber glass coating present on the 1157NA used in surrounding model years for that same position.
All three bulb types carry ANSI standard designation applicable to both the United States and Canada, indicating conformance to a shared North American specification.