Plymouth Concord Back Up Light Bulb Size

The Plymouth Concord back up light requires a bulb size of 1129 for the rear lighting assembly. Data for the specific bulb requirements covers the range from 1951 to 1952.

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
1951-1952	1129

Bulb Specifications

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

Other Locations

Additional Notes

The 1129 bulb is the specified back up light bulb size for the Plymouth Concord across the 1951-1952 model years.
The 1129 is an ANSI-standard bulb recognized in both the United States and Canada, operating at 12 volts with a dual-filament design rated at 21/5 watts.
A dual-filament bulb contains two separate filaments within a single envelope, each serving a distinct lighting function at different wattages.
The 1129 uses a BAY15d bayonet base, a two-pin offset bayonet mount where the two pins are positioned at different heights to ensure correct orientation during installation.
The 1129 is a variant of the 1157 bulb, meaning the two share a close relationship in design, though they are not confirmed as interchangeable for this application without further verification against the specific socket and circuit requirements of the Plymouth Concord.