Chevrolet Chevy II Back Up Light Bulb Size

The Chevrolet Chevy II back up light uses 1156 and P21W bulb sizes for the lighting components. Available information covers the period from 1962 through 1968 for the specified vehicle.

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
1962-1968	1156

Bulb Specifications

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

Other Locations

Additional Notes

The 1156 is the sole back up light bulb size listed across all Chevrolet Chevy II model years in these specifications, covering 1962-1968.
The 1156 is an ANSI-standardized bulb type recognized in both the United States and Canada.
It is a single-filament bulb, meaning it serves one lighting function rather than combining two, such as stop and tail duties, into a shared housing.
The 1156 operates on a 12-volt electrical system at 21 watts, which is consistent with the standard automotive electrical architecture of that era.
Its base type is the BA15s bayonet mount, a single-contact design where the "s" denotes a single pin. This distinguishes it from the dual-contact BA15d base found on two-filament variants.
The BA15s base requires rotational alignment during installation, as the single offset pin locks the bulb into a fixed position within the socket.
Because the 1156 and the visually similar 1157 share the same BA15s-style housing profile, substitution between the two is not interchangeable. The 1157 carries a dual-contact base and two filaments, making it electrically incompatible with a single-contact 1156 socket.