The Chevrolet Classic front turn signal requires a 3157NA bulb size while the rear turn signal uses a 2456 bulb size. The replacement chart covers 2004 to 2005 vehicle production years with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Chevrolet Classic (2004-2005) uses two distinct bulb types across its front and rear turn signal positions: the 3157NA for the front and the 2456 for the rear.
The 3157NA is a dual-filament bulb, meaning it carries two separate filaments within a single housing, each operating at a different wattage. The higher-draw filament runs at 27W and the lower at 7W, allowing one bulb to serve both a bright signaling function and a reduced-intensity parking or running light function.
The 3157NA is housed in a T25 wedge-style base, which is a push-and-twist type fitting common in automotive lighting. Its natural amber glass gives the emitted light an amber color without relying on a colored lens or coating.
Both the 3157NA and the 2456 conform to ANSI standards and are rated for use in the United States and Canada, placing them within a standardized North American bulb classification system.
The 2456 is a festoon-type bulb, a cylindrical form factor held in place by spring-loaded end caps rather than a socket base. This construction is associated with specialty applications where space or mounting orientation differs from standard socket positions.
Both bulbs operate on a 12V electrical system, which is consistent with the standard automotive voltage found in passenger vehicles of this type.
The 3157NA designation is a specific variant within the broader 3157 bulb family. The "NA" suffix indicates the natural amber glass envelope, which distinguishes it from clear-glass versions of the same base type. Substituting a clear 3157 in place of a 3157NA would alter the color output of the front turn signal.
Because the 3157NA is dual-filament and the 2456 is a festoon type, the two bulbs are not interchangeable with each other, as they differ in base type, filament count, wattage, and physical form.