Buick Wildcat Back Up Light Bulb Size

The Buick Wildcat back up light requires bulb sizes 1073, 1156, or P21W depending on the specific application. Available data covers the production period from 1962 through 1970.

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
1964-1970	1156
1963	1073
1962	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 back up light bulbs specified for the Buick Wildcat across its 1962-1970 model years are drawn from two ANSI-standard bulb types: the 1156 and the 1073.
Both the 1156 and 1073 are single-filament bulbs sharing the BA15s bayonet base and a 12-volt operating voltage.
The BA15s bayonet base is a single-contact base, which is the standard fitment for single-filament automotive applications.
The 1156 operates at 21 watts, while the 1073 operates at 13 watts, making the 1073 a lower-wattage variant within the same base family.
Despite sharing the same BA15s base, the wattage difference between the 1156 and 1073 means the two bulbs are not direct substitutes for one another without accounting for the output difference.
The 1156 is the specified back up light bulb for the Buick Wildcat across the majority of its model years, covering 1962 and 1964-1970.
The 1073 is specified exclusively for the 1963 Buick Wildcat, setting that model year apart from all others in this specification set.
Both bulb types carry ANSI standardization applicable to the US and Canadian markets.