GMC R3500 Back Up Light Bulb Size
The GMC R3500 back up light requires 3156, 1156, or P21W bulb sizes depending on the specific version of the component. Data for the bulb sizes covers the range from 1987 to 1991.
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 | US Type | EU Type | Shop |
|---|---|---|---|
| 1990-1991 | 3156 | P27W | Check Price |
| 1987-1989 | 1156 | P21W | Check Price |
Bulb Specifications
| Description | Type | Shop |
|---|---|---|
| ANSI standard (US & Canada). Single-filament wedge bulb (T25). 12V, 27W. | 3156 | Check Price |
| ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 21W. | 1156 | Check Price |
| ECE standard (Europe & worldwide). Single-filament signalling bulb with BA15s bayonet base. 12V, 21W. | P21W | Check Price |