International 200 Back Up Light Bulb Size

The International 200 back up light requires a P21W bulb size for proper installation and function within the rear lighting assembly. Data for the specified bulb 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
1974-1975	P21W

Bulb Specifications

Description	Bulb Size
ECE standard (Europe & worldwide). Single-filament signalling bulb with BA15s bayonet base. 12V, 21W.	P21W

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Additional Notes

The P21W is the specified back up light bulb for the International 200 across the 1974-1975 model years.
The P21W is an ECE-standard single-filament signalling bulb rated at 12 volts and 21 watts, fitted with a BA15s bayonet base.
The BA15s bayonet base uses a single-contact configuration, which is a key fitment detail distinguishing it from visually similar bases such as the dual-contact BA15d.
The ECE designation indicates the P21W was developed under European and international regulatory standards, making it a globally recognized bulb type rather than a market-specific one.
At 21 watts, the P21W delivers a relatively high output for a single-filament signalling bulb, which is consistent with its use in back up light applications where visibility is a functional requirement.
The single-filament construction of the P21W means it serves one lighting function only, as opposed to dual-filament bulbs that combine two functions such as stop and tail in a single unit.