International 150 Back Up Light Bulb Size

The International 150 back up light requires bulb size 199 or P21W depending on the specific application. Data for the bulb sizes covers the range from 1974 to 1975.

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
1975	P21W
1974	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 P21W and 199 bulbs are the two back up light bulb types specified for the International 150, covering the 1974-1975 model years.
Both the P21W and 199 operate at 12 volts with a 21-watt output, placing them in the same power class for single-filament signalling applications.
Both bulbs share the BA15s bayonet base, a single-contact base type where the "s" denotes a single pin offset to one side of the base.
The P21W is governed by ECE standards, which are used in Europe and internationally, while the 199 follows ANSI standards applicable in the US and Canada.
The 199 is a variant of the 1156 bulb, meaning it shares the same fundamental construction and base type as that widely used ANSI-standard bulb.
Because the P21W and 199 share identical voltage, wattage, and base type, their physical and electrical compatibility is closely aligned despite originating from different standardization bodies.
The International 150 (1975) is specified with the P21W, while the 1974 model uses the 199, indicating that the two bulb types are not interchangeable across all model years without confirming the specific year.