Ford Gran Torino License Plate Bulb Size

The Ford Gran Torino license plate light requires a 631 bulb size for the specific lighting component located at the rear of the vehicle. Available data for the bulb covers the period from 1972 to 1973.

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 Type	Shop
1972-1973	631	Check Price

Bulb Specifications

Description	Type	Shop
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Variant of 1156. 12V, 21W.	631	Check Price

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Additional Notes

The 631 bulb follows the ANSI standard recognized in both the United States and Canada, making it a regionally standardized component rather than a proprietary specification.
The 631 is a single-filament bulb, meaning it serves one lighting function only, which is consistent with the straightforward on/off role of a license plate light.
It uses a BA15s bayonet base, a single-contact fitting where the "s" denotes a single pin offset to one side, distinguishing it from dual-contact bayonet bases used in other applications.
The 631 is rated at 12 volts and 21 watts, placing it in the standard low-voltage automotive range typical of 12V vehicle electrical systems.
The Ford Gran Torino (1972-1973) uses the 631 bulb for its license plate lighting across both model years covered in the specifications.
The 631 is noted as a variant of the 1156 bulb. While they share the BA15s base and general construction, they are not confirmed as direct drop-in replacements for one another without verifying voltage and wattage compatibility in a given socket.