GMC C15 Suburban License Plate Bulb Size

The GMC C15 Suburban license plate light requires a unique bulb size of 97 for proper installation. Data for the specified lighting component 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

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Additional Notes

The bulb type specified across all listed model years of the GMC C15 Suburban is the 97, an ANSI-standardized bulb recognized in both the United States and Canada.
The 97 bulb operates on a 12-volt electrical system and draws 13 watts, which is typical of low-load automotive lighting circuits such as license plate illumination.
A single filament is present in the 97 bulb, meaning it serves one lighting function only, with no secondary brightness mode or dual-circuit capability.
The 97 uses a BA15s bayonet base, a single-contact mount where the bulb is inserted and rotated to lock into place, as opposed to a screw or wedge-style fitting.
The 97 is noted as a variant of the 1156 bulb. While the two share the BA15s base type, they are not identical, and substitution between them may not be appropriate in all applications.
The license plate bulb size for the GMC C15 Suburban remains the 97 across the 1973-1978 model years without variation.