Chevrolet Bel Air Courtesy Bulb Size

The Chevrolet Bel Air courtesy light uses bulb sizes 1004, 211-2, 89, 631, and 90 depending on the specific version of the vehicle. Available information covers the range from 1955 through 1975 for the specified lighting components.

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
1975	1004
1974	211-2
1972-1973	89
1968-1971	631
1967	90
1964-1966	631
1955-1963	89

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base. Variant of 1157. 12V, 21/5W.	1004
ANSI standard (US & Canada). Festoon bulb, 41mm length, SV8.5 base. 12V, 12W.	211-2
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. Variant of 1156. 12V, 21W.	631
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 13W.	90

Other Locations

Additional Notes

The bulb type 631 is the most frequently specified courtesy bulb across the Chevrolet Bel Air's model history, covering the 1964-1966 and 1968-1970 model years. It is an ANSI-standard single-filament bulb with a BA15s bayonet base, rated at 12V and 21W, and is classified as a variant of the 1156.
The bulb type 89 is the second most common specification, used across the 1955-1963 and 1972-1973 model years. It is an ANSI-standard single-filament bulb with a BA15s bayonet base, rated at 12V and 13W, and is described as a lower wattage variant of the 1156.
Both the 631 and the 89 share the BA15s bayonet base, meaning they are physically similar in mounting style. However, their wattage ratings differ significantly, at 21W and 13W respectively, which means they are not interchangeable without accounting for the difference in power draw.
The bulb type 90, specified for the 1967 Chevrolet Bel Air, also uses the BA15s bayonet base and is rated at 12V and 13W. Its wattage matches the 89, though the two carry distinct ANSI designations and are listed as separate types within the specifications.
The 1975 Bel Air uses the 1004 bulb, which is a dual-filament type with a BAY15d bayonet base, rated at 12V and 21/5W. The BAY15d base differs from the BA15s base used by the 89, 90, and 631 types, making the 1004 physically incompatible with sockets designed for those single-filament bulbs.
The 1974 Bel Air uses the 211-2, a festoon-style bulb with an SV8.5 base and a 41mm length, rated at 12V and 12W. The festoon format is structurally distinct from the bayonet-base bulbs used in all other model years listed, as it mounts by contact pressure at each end rather than by a twist-lock base.
The BAY15d base of the 1004 bulb features an offset pin arrangement that prevents it from being inserted into a standard BA15s socket, which is relevant when considering the 1975 model year against earlier Bel Air courtesy bulb applications.
All bulb types listed across the Bel Air courtesy bulb specifications conform to ANSI standards applicable in both the United States and Canada, and all are rated for 12-volt electrical systems.