Pontiac Star Chief Back Up Light Bulb Size

The Pontiac Star Chief back up light utilizes unique bulb sizes 1156, P21W, 1073, and 1129 depending on the specific production version. Available data covers the range from 1954 through 1966 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
1958-1966	1156
1955-1957	1073
1954	1129

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
ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base. Variant of 1157. 12V, 21/5W.	1129

Other Locations

Additional Notes

The Pontiac Star Chief back up light specifications span model years 1954 through 1966, covering three distinct bulb types across that range.
The 1156 bulb is the most frequently specified type, appearing across the Star Chief from 1958 through 1966.
The 1156 is an ANSI-standard single-filament bulb rated at 12V and 21W, fitted with a BA15s bayonet base, which uses a single locating pin for socket alignment and retention.
The 1073 bulb was specified for the Pontiac Star Chief across model years 1955-1957 and shares the same BA15s bayonet base as the 1156.
Although the 1073 and 1156 share the BA15s base, the 1073 operates at 13W compared to the 1156's 21W, making them lower-output variants of the same base type rather than direct substitutes in all applications.
The 1954 Star Chief back up light uses the 1129 bulb, which differs fundamentally from the other two types in that it is a dual-filament bulb rated at 21/5W.
The 1129 uses a BAY15d bayonet base, which features two offset locating pins to prevent incorrect installation, distinguishing it physically from the single-pin BA15s base used by both the 1156 and 1073.
Because the 1129 uses a BAY15d base and the 1156 and 1073 use a BA15s base, these bulb types are not interchangeable despite sharing a 12V operating voltage.
The 1129 is noted as a variant of the 1157, a widely recognized dual-filament automotive bulb, while the 1073 is noted as a lower-wattage variant of the 1156.
All three bulb types in these specifications conform to ANSI standards applicable in the United States and Canada.