Buick Estate Wagon Back Up Light Bulb Size

The Buick Estate Wagon back up light utilizes 1156, 1073, and P21W bulb sizes for the exterior lighting system. Available information covers a range from 1959 through 1983.

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
1970-1983	1156
1963-1964	1156
1962	1073
1959-1961	1156

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 21W.	1156
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Lower wattage variant of 1156. 12V, 13W.	1073

Other Locations

Additional Notes

The Buick Estate Wagon uses the 1156 bulb as the back up light bulb for model years 1959-1964 and 1970-1983, making it the dominant fitment across the production span covered by these specifications.
The 1156 is an ANSI-standard single-filament bulb rated at 12 volts and 21 watts, fitted with a BA15s bayonet base, and recognized under both US and Canadian standards.
The BA15s bayonet base designation indicates a single-contact base with a 15mm barrel, which locks into the socket with a push-and-twist motion rather than a threaded connection.
The 1962 Buick Estate Wagon is the sole model year in these specifications fitted with the 1073 bulb rather than the 1156.
The 1073 is also an ANSI-standard single-filament bulb with a BA15s bayonet base rated at 12 volts, but it operates at 13 watts, notably lower than the 21 watts of the 1156.
Although the 1156 and 1073 share the same BA15s bayonet base, the wattage difference means the two bulbs are not direct equivalents, and substituting one for the other affects light output.
The single-filament construction of both the 1156 and 1073 is consistent with back up light applications, which require only one steady light function rather than the dual functions associated with combination stop and tail bulbs.