GMC C15 License Plate Bulb Size

The GMC C15 license plate light uses a unique bulb size identified as 97 for the specified lighting component. Data for the bulb size covers the range from 1975 to 1978.

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
1973-1978	97

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Variant of 1156. 12V, 13W.	97

Other Locations

Additional Notes

The GMC C15 uses the ANSI-standard 97 bulb for the license plate position across the 1973-1978 model years.
The 97 bulb operates on a 12-volt electrical system and draws 13 watts, placing it in the low-wattage range typical of auxiliary lighting applications.
The 97 bulb is a single-filament type, meaning it serves one lighting function only, with no secondary filament for a dimming or braking mode.
The BA15s designation refers to a single-contact bayonet base with a 15mm collar, which is the physical mounting interface used to secure and connect the bulb.
The 97 bulb is noted as a variant of the 1156, though the two are not directly interchangeable due to differences in wattage and base contact configuration despite sharing the BA15s base style.
The ANSI classification of the 97 bulb indicates it meets a standardized specification recognized in both the United States and Canada.