Chevrolet C-Series Pickup Turn Signal Bulb Size

Additional Notes

• The 2357NA bulb is the most frequently specified front turn signal bulb across the Chevrolet C-Series Pickup range, appearing in model years 1988-1991 and 1993-2000, with the exception of 1992. It is a dual-filament bulb with a BAY15d bayonet base and natural amber glass, rated at 12V with a 26.9W high-filament and 8W low-filament output.
• The "NA" suffix present on bulb designations such as 2357NA, 3057NA, 2057NA, and 1157NA denotes natural amber glass, meaning the amber color is built into the glass envelope rather than produced by a colored lens or housing. This distinction is relevant where housing color affects the final light output.
• The 1157 and 1157NA share identical wattage ratings of 21W/5W at 12V with a BAY15d bayonet base, differing only in glass color. The 2057 and 2057NA are described as brighter variants of the 1157 family, operating at 26.9W/8W, and share the same BAY15d base type, which can create a risk of substitution errors despite the wattage difference.
• The 3057 and 3057NA are dual-filament wedge bulbs of the T25 form factor, rated at 27W/7W at 12V. This base type is physically distinct from the BAY15d bayonet base used by the 1157, 2057, and 2357 families, making cross-family substitution mechanically incompatible.
• The 1986 and 1985 Chevrolet C-Series Pickup front turn signal position requires different bulbs depending on headlamp configuration. Vehicles with two headlamps use the 3057NA, while those with four headlamps use the 2057NA. These two bulbs differ in both base type and wattage, making headlamp count a necessary factor in bulb selection for those years.
• The 1992 front turn signal position is specified as 3057, which is a T25 wedge bulb, while all surrounding model years use the 2357NA with a BAY15d bayonet base. The two base types are not interchangeable, and the socket type for that year differs from the majority of the production range.
• The 198 bulb, specified for both front and rear turn signal positions in 1975-1978, is a miniature T5 wedge bulb rated at only 2W at 12V. This output is substantially lower than all other bulb types listed in the specifications, reflecting a different lamp assembly design used during that period.
• The rear turn signal position shows variation across individual model years rather than a consistent bulb type, with the 1157, 3057, and 2057 appearing in alternating years between 1988 and 2000. Since the 3057 uses a T25 wedge base and the 1157 and 2057 use a BAY15d bayonet base, the correct base type must be confirmed against the specific model year before replacement.