The Chevrolet P60 front turn signal bulb size measures 1157 or 2057, while the rear turn signal bulb size measures 1157. The replacement chart covers 1983 through 1988 vehicle production 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 is the most widely used bulb across these specifications, appearing in both the front and rear turn signal positions for the Chevrolet P60 across the majority of the listed model years.
The 1157 is a dual-filament bulb rated at 12V with a 21W high filament and a 5W low filament, mounted on a BAY15d bayonet base, and classified under the ANSI standard applicable in the US and Canada.
The 2057 shares the same BAY15d bayonet base as the 1157 and operates at 12V, but draws higher wattage at 26.9W on the high filament and 8W on the low filament, making it a brighter variant within the same base family.
Because the 1157 and 2057 share the same BAY15d bayonet base, they are physically interchangeable in terms of socket fitment, though their electrical output differs.
The 1984 Chevrolet P60 front turn signal position specifies the 2057 rather than the 1157, which sets that year apart from all other listed model years in the front turn signal application.
The rear turn signal position on the P60 uses the 1157 consistently across all listed years from 1983-1988, with no variation recorded in that position.
Substituting a 1157 for a 2057 in the 1984 front turn signal position would result in reduced output, as the 1157 high filament draws 21W compared to the 2057's 26.9W high filament rating.
Both the 1157 and 2057 are dual-filament designs, meaning a single bulb serves two functions, typically combining turn signal operation with a secondary running or parking light function.