Chevrolet Chevy II Courtesy Bulb Size

The Chevrolet Chevy II uses courtesy light components with 631 and 89 bulb sizes depending on the specific version of the vehicle. Data for the bulb sizes covers the range from 1962 through 1968.

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
1964-1968	631
1962-1963	89

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Variant of 1156. 12V, 21W.	631
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Lower wattage variant of 1156. 12V, 13W.	89

Other Locations

Additional Notes

The Chevrolet Chevy II uses two distinct bulb types across its courtesy light specifications: the 631 and the 89, both classified under ANSI standards applicable to the US and Canadian markets.
Both the 631 and the 89 share the BA15s single-contact bayonet base, meaning they are physically compatible with the same socket type despite differing in wattage output.
The 631 bulb operates at 12 volts and draws 21 watts, while the 89 operates at 12 volts and draws 13 watts, making the 89 a lower-wattage variant within the same base family.
Both bulbs are single-filament types, which is consistent with courtesy lighting applications that require simple on/off switching rather than dual-intensity output.
The 631 is described as a variant of the 1156, sharing its BA15s base but differing in wattage, and it serves as the courtesy bulb for the Chevrolet Chevy II across the 1964-1968 model years.
The 89 bulb, also a lower-wattage variant of the 1156, was specified for the 1962-1963 model years of the Chevy II.
Although the 631 and 89 share the same BA15s bayonet base, substituting one for the other would result in a wattage difference of 8 watts, which may affect circuit load and light output.