GMC R2500 License Plate Bulb Size

The GMC R2500 license plate light uses 194 and 67 bulb sizes for the lighting components. Available data for the specified vehicle covers the range from 1987 to 1989.

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
1988-1989	194
1987	67

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Miniature wedge bulb (T10). 12V, 3.78W.	194
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Lower wattage variant of 1156. 12V, 8W.	67

Other Locations

Additional Notes

The 194 bulb is the most frequently specified license plate bulb for the GMC R2500, covering the 1988-1989 model years.
The 194 is a T10 miniature wedge bulb rated at 12V and 3.78W, conforming to ANSI standards recognized in both the United States and Canada.
The wedge base of the 194 bulb requires no metal base or locking pins, as the glass envelope itself acts as the retention mechanism within the socket.
The 1987 GMC R2500 uses the 67 bulb for the license plate position, which differs in both base type and wattage from the 194 used in subsequent model years.
The 67 bulb operates at 12V and 8W, making it notably higher in wattage than the 194, which draws only 3.78W.
The 67 bulb uses a BA15s single-contact bayonet base, a twist-and-lock style mount that is physically incompatible with the wedge socket used by the 194.
The 67 is described as a lower wattage variant of the 1156 bulb, sharing the same BA15s bayonet base but producing less output, which means a 1156 is not a direct substitute for the 67 in this application.
The base type difference between the 67 and the 194 means these two bulbs are not interchangeable across the 1987 and 1988-1989 model years of the R2500.