Chrysler 300 Back Up Light Bulb Size

The Chrysler 300 back up light utilizes 921, 7440, P21W, 1156, 1073, and 1129 bulb sizes for the rear exterior illumination. Available information for the specified vehicle covers the period from 1955 through 2021.

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
2021	921
2011-2014	7440
1968-1971	1156
1967	1073
1966	1156
1962-1965	1073
1958-1961	1156
1956-1957	1073
1955	1129

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Wedge bulb (T15). 12V, 16W.	921
ANSI standard (US & Canada). Single-filament wedge bulb (T20). 12V, 21W.	7440
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 Chrysler 300 back up light specifications reference five distinct bulb types across model years: the 921, 7440, 1156, 1073, and 1129.
The 7440 is a T20 single-filament wedge bulb rated at 12V and 21W, and it is specified for the Chrysler 300 across the 2011-2014 model years.
The 921 is a T15 wedge bulb rated at 12V and 16W, and it is specified for the 2021 model year. Although both the 921 and 7440 are wedge-type bulbs, they differ in size and wattage, making them non-interchangeable.
The 1156 carries a BA15s single-contact bayonet base and is rated at 12V and 21W. It appears across multiple non-consecutive model years spanning 1958-1971.
The 1073 also uses a BA15s bayonet base and is rated at 12V and 13W, making it a lower-wattage variant of the 1156. Despite sharing the same base type, the wattage difference means the two bulbs are not direct substitutes in applications where output levels are a factor.
The 1129 is the only dual-filament bulb in these specifications, carrying a BAY15d bayonet base and rated at 12V with a 21/5W output. The BAY15d base has two offset pins, distinguishing it physically from the single-contact BA15s base used by the 1073 and 1156.
The 1129 is specified exclusively for the 1955 Chrysler 300, the earliest model year in these specifications, and it is the sole instance of a dual-filament bulb across all listed years.
All five bulb types conform to ANSI standards applicable in both the United States and Canada.
The 1073 is specified for the 1956-1957, 1962-1965, and 1967 model years, while the 1156 is specified for 1958-1961, 1966, and 1968-1971, indicating that the two BA15s-based bulbs alternated across successive generations of the model.
The wedge-base bulbs specified for 2011-2014 and 2021 are physically incompatible with the bayonet-base bulbs specified for the 1955-1971 model years, as the two base types require different socket designs.