Plymouth PB100 Back Up Light Bulb Size

The Plymouth PB100 back up light requires bulb size 199 or P21W depending on the specific application for the vehicle. Data for the bulb sizes covers the range from 1975 to 1980.

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
1979-1980	P21W
1977-1978	199
1976	P21W
1975	199

Bulb Specifications

Description	Bulb Size
ECE standard (Europe & worldwide). Single-filament signalling bulb with BA15s bayonet base. 12V, 21W.	P21W
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Variant of 1156. 12V, 21W.	199

Other Locations

Additional Notes

The Plymouth PB100 backup light specifications cover model years 1975-1980, with two bulb types appearing across that span: the P21W and the 199.
Both the P21W and the 199 are single-filament bulbs rated at 12V and 21W, sharing identical electrical output despite originating from different standardization systems.
The P21W follows the ECE standard, which governs automotive lighting across Europe and much of the world, while the 199 follows the ANSI standard used in the United States and Canada.
Both bulb types use a BA15s bayonet base, meaning the physical mounting interface is the same between the two.
The shared BA15s base, voltage, and wattage between the P21W and the 199 indicate a high degree of interchangeability in practical fitment, though the differing standards from which each originates should be noted.
The Plymouth PB100 used the 199 bulb in 1975, 1977, and 1978, while the P21W was specified for 1976, 1979, and 1980.
The 199 is described as a variant of the 1156, which is a widely used ANSI single-filament automotive bulb, placing the 199 within a well-established North American bulb family.