GMC C7000 License Plate Bulb Size

The GMC C7000 license plate light requires a 67 bulb size for proper illumination of the rear identification area. Data for the specified component covers the range from 1979 through 1990.

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
1985-1990	67 (Tiltmaster)
1984	67
1983	67 (Medium Duty)
1979-1980	67

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Lower wattage variant of 1156. 12V, 8W.	67

Other Locations

Additional Notes

The bulb size 67 is an ANSI-standardized single-filament bulb rated at 12 volts and 8 watts, fitted with a BA15s bayonet base. It is a lower-wattage variant of the more widely known 1156 bulb, which shares the same base type but operates at a higher wattage.
The BA15s bayonet base uses a single contact pin, which is a key fitment detail. Bulbs with a BA15d base, which carries two offset pins, are not interchangeable with the size 67 even though the two base types appear physically similar at a glance.
The GMC C7000 uses the size 67 bulb for the license plate position across the 1979-1990 model years covered in these specifications.
The 1985-1990 model years carry a "Tiltmaster" designation alongside the size 67 fitment, indicating those entries apply specifically to the Tiltmaster variant of the C7000.
The 1983 model year entry carries a "Medium Duty" designation, distinguishing it from the Tiltmaster-labeled entries and the unlabeled entries for other years.
Because the size 67 is a lower-wattage bulb than the 1156, substituting a 1156 in a socket rated for the size 67 risks exceeding the designed electrical load for that circuit.