Chevrolet Chevelle front turn signal bulbs utilize 1157 or 1157NA size specifications, while rear turn signal bulbs require 1157 size bulbs. The replacement chart covers 1964 through 1973 production years with corresponding bulb size data.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 1157 is the dominant bulb type across the turn signal specifications for the Chevrolet Chevelle, appearing in both front and rear positions across the 1964-1973 model years.
The 1157 operates at 12 volts and carries a dual-filament design rated at 21W and 5W, where the higher-wattage filament serves the active turn signal function and the lower-wattage filament serves a parking or running light function.
The 1157 uses a BAY15d bayonet base, a two-pin offset base type that physically prevents incorrect insertion by positioning its two pins at different heights along the base.
The 1157NA variant was specified for the front turn signal position on the 1969 Chevelle only, while the rear turn signal for that same year retained the standard 1157.
The 1157NA shares the same 12V, 21W/5W dual-filament configuration and BAY15d bayonet base as the 1157, differing only in its natural amber-tinted glass envelope, which produces an amber output without relying on a colored lens.
Because the 1157 and 1157NA are electrically and mechanically identical, the distinction between them is optical rather than functional, meaning socket fitment is the same for both.
Both the 1157 and 1157NA are classified under ANSI standards recognized in the United States and Canada, indicating standardized electrical and physical tolerances across manufacturers.
The rear turn signal position on the Chevelle used the standard 1157 without variation across all ten model years listed in the specifications, from 1964 through 1973.