Chevrolet Chevelle Parking Light Bulb Size

Additional Notes

• The 1157 bulb is the dominant parking light specification across the Chevrolet Chevelle, covering the 1964-1968 and 1970-1973 model years.
• The 1157 is a dual-filament bulb, meaning it carries two separate filaments within a single envelope, one rated at 21W and the other at 5W, allowing it to serve both a brighter active state and a dimmer standing-light state.
• Both the 1157 and 1157NA use the BAY15d bayonet base, a two-pin offset base design that physically locks the bulb into the socket with a quarter-turn motion.
• Both variants operate on a 12V electrical system and share identical wattage ratings of 21W and 5W, making their electrical characteristics equivalent.
• The 1157NA specified for the 1969 Chevelle differs from the standard 1157 solely in its natural amber glass envelope, which produces an amber-tinted output without the use of an external amber lens or filter.
• Because the 1157 and 1157NA share the same BAY15d base and identical voltage and wattage ratings, the two types are physically interchangeable in terms of socket fitment, though substituting one for the other alters the color output of the light.
• The ANSI designation on both bulb types indicates conformance to a standardized specification recognized across the United States and Canada, governing the physical and electrical parameters of each type.
• The dual-filament configuration of the 1157 is a common arrangement in parking light applications where the same housing serves more than one lighting function, such as parking and turn signal duties simultaneously.