Chevrolet Brookwood Parking Light Bulb Size

Additional Notes

• The 1157 and 1034 are both ANSI-standardized bulb types recognized across the United States and Canada, and both follow a dual-filament design mounted on a BAY15d bayonet base.
• A dual-filament bulb contains two separate filaments within a single envelope, allowing it to serve two distinct lighting functions, such as running light and brake light, from one unit.
• The BAY15d bayonet base uses two offset pins to ensure correct rotational alignment during installation, distinguishing it from single-pin bayonet bases used in single-filament bulbs.
• Both bulb types operate at 12 volts with a 21W/5W power split, where the higher wattage filament serves the brighter signaling function and the lower wattage filament serves the dimmer running light function.
• The Chevrolet Brookwood uses the 1034 bulb for parking lights across the 1958-1961 model years.
• The 1034 is described as a variant of the 1157, meaning the two types share the same base configuration and voltage-wattage ratings but are not the same part number and are not confirmed as interchangeable.
• The 1157 bulb applies to the Brookwood's parking lights across the 1969-1972 model years, representing the later production period covered by these specifications.