Chevrolet Astro Turn Signal Bulb Size

Chevrolet Astro front and rear turn signal bulbs utilize 3157NA and 2057 bulb sizes respectively. The replacement chart covers 1985 to 2005 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.

Front Turn Signal

If US Type and EU Type show the same value, a direct cross-reference for this bulb is not available or the data is insufficient.

Years	US Type	EU Type	Shop
1995-2005	3157NA	PY27/7W	Check Price
1985-1994	2057	2057	Check Price

Rear Turn Signal

Years	Bulb Type	Shop
1985-2005	2057	Check Price

Bulb Specifications

Description	Type	Shop
ANSI standard (US & Canada). Dual-filament wedge bulb (T25), natural amber glass. 12V, 27W/7W.	3157NA	Check Price
ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base. Brighter variant of 1157. 12V, 26.9W/8W.	2057	Check Price

Other Locations

Additional Notes

The 2057 bulb follows the ANSI standard for the US and Canada markets. It uses a BAY15d bayonet base and operates on 12V with a dual-filament configuration rated at 26.9W for the high-intensity filament and 8W for the low-intensity filament. The higher wattage filament activates for turn signaling, while the lower wattage filament serves a secondary function such as running or parking light duty.
The 3157NA shares the same dual-filament design but uses a T25 wedge base rather than a bayonet mount. Its ratings are 12V at 27W/7W. The "NA" designation indicates natural amber glass, meaning the bulb itself produces an amber output without relying on a colored lens to achieve the required turn signal color.
The Chevrolet Astro front turn signal used the 2057 bulb from 1985-1994, then transitioned to the 3157NA from 1995-2005. These two bulb types use different base configurations, a BAY15d bayonet and a T25 wedge respectively, making them physically non-interchangeable despite their similar wattage ratings.
The rear turn signal position used the 2057 bulb across the entire 1985-2005 production span without any change in specification. This means the front and rear turn signal positions required different bulbs for model years 1995-2005, when the front had already moved to the 3157NA.
The 2057 is noted as a brighter variant of the 1157 bulb. Both share the BAY15d bayonet base, but the 2057 produces higher output on its primary filament. This distinction is relevant when considering substitutions, as an 1157 is not a direct equivalent despite the physical compatibility of the base.