Plymouth Belvedere II Back Up Light Bulb Size

The Plymouth Belvedere II back up light requires bulb size 1073 or P21W depending on the specific application. Data for the bulb size covers the range from 1965 to 1967.

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
1967	1073
1965-1966	P21W

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Lower wattage variant of 1156. 12V, 13W.	1073
ECE standard (Europe & worldwide). Single-filament signalling bulb with BA15s bayonet base. 12V, 21W.	P21W

Other Locations

Additional Notes

The Plymouth Belvedere II back up light specifications cover the 1965-1967 model years, with two distinct bulb types listed across that span.
The 1073 is an ANSI-standard bulb used in North American markets, operating at 12V and 13W with a single filament and a BA15s bayonet base.
The P21W is an ECE-standard bulb associated with European and worldwide markets, operating at 12V and 21W with a single filament and a BA15s bayonet base.
The 1967 Plymouth Belvedere II specifies the 1073 bulb for the back up light position, while the 1965-1966 model years specify the P21W.
Both the 1073 and P21W share the BA15s bayonet base, meaning the physical mounting interface is identical between the two bulb types.
Despite the shared base, the 1073 and P21W differ significantly in wattage, with the P21W rated at 21W compared to the 1073 at 13W, making them non-equivalent substitutes in terms of electrical load.
The 1073 is described as a lower wattage variant of the 1156, a common ANSI single-filament bulb also using the BA15s base, which places the 1073 within a well-established family of North American automotive bulbs.
The shift from P21W in 1965-1966 to the 1073 in 1967 reflects a change in the specified standard between those model years for the Belvedere II back up light.