Chevrolet El Camino Back Up Light Bulb Size

The Chevrolet El Camino back up light utilizes 1156, 1073, and P21W bulb sizes depending on the specific production period for the vehicle. Available data covers the range from 1959 to 1987 for the components listed.

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
1964-1987	1156
1960	1073
1959	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 Chevrolet El Camino back up light specifications cover model years 1959-1987, with the 1156 bulb designated for the overwhelming majority of that range.
The 1156 is an ANSI-standard single-filament bulb rated at 12V and 21W, fitted with a BA15s bayonet base, which is a single-contact base with a 15mm collar.
The 1073 bulb shares the same BA15s bayonet base and 12V operating voltage as the 1156 but draws only 13W, making it a lower-output variant of the same base type.
Because the 1073 and 1156 share the same BA15s bayonet base, they are physically interchangeable in the socket, though their wattage ratings differ and substitution between them is not indicated by the specifications.
The Chevrolet El Camino (1960) is the sole model year in the specifications assigned the 1073 bulb for the back up light position.
The 1959 model year uses the 1156 rather than the 1073, meaning the two adjacent model years carry different bulb designations despite sharing the same socket base type.
From 1964 through 1987, the 1156 bulb is specified without interruption across all listed model years, representing a continuous 24-year fitment period for that single bulb designation.
Both the 1156 and 1073 are classified under ANSI standards applicable to the United States and Canada, indicating a standardized North American specification for these bulb types.
Single-filament construction in both bulb types means each serves only one lighting function per socket, which is consistent with a dedicated back up light application.
The BA15s designation denotes a single-contact bayonet base, distinguishing these bulbs from dual-contact BA15d variants that are used in two-filament applications.