Chevrolet Biscayne Trunk Bulb Size

The Chevrolet Biscayne trunk utilizes bulb sizes 89 and 1003 for illumination across various production versions. Provided information covers the specific time span from 1958 through 1972.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Bulb Size by Year Range

Years	Bulb Size
1972	89
1958-1971	1003

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Lower wattage variant of 1156. 12V, 13W.	89
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 21W.	1003

Other Locations

Additional Notes

The 1003 bulb is the trunk bulb for the Chevrolet Biscayne across 1958-1971, making it the dominant fitment across this model's trunk lighting specifications.
The 1003 is an ANSI-standard single-filament bulb rated at 12V and 21W, fitted with a BA15s bayonet base.
The 1972 Biscayne uses the 89 bulb for the trunk, which differs from all prior model years in this specification set.
The 89 bulb is also an ANSI-standard single-filament bulb with a BA15s bayonet base, rated at 12V and 13W, making it a lower-wattage unit than the 1003.
Although both the 89 and 1003 share the same BA15s bayonet base type, their wattage ratings differ by 8W, and the two bulbs are not interchangeable despite the physical base compatibility.