GMC G25 Turn Signal Bulb Size
The GMC G25 front and rear turn signal bulb sizes include 198, 199, 1156, and 1073 options, with the front position utilizing 198, 199, or 1156 bulbs and the rear position utilizing 198, 1156, or 1073 bulbs. The replacement chart covers vehicle production years from 1967 through 1978, detailing bulb specifications across the entire production span.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
Front Turn Signal
| Years | Bulb Size |
|---|---|
| 1973-1978 | 198 |
| 1971-1972 | 199 |
| 1968-1970 | 1156 |
| 1967 | 1034 |
Rear Turn Signal
| Years | Bulb Size |
|---|---|
| 1973-1978 | 198 |
| 1969-1972 | 1156 |
| 1967-1968 | 1073 |
Bulb Specifications
| Description | Bulb Size |
|---|---|
| ANSI standard (US & Canada). Miniature wedge bulb (T5). 12V, 2W. | 198 |
| ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Variant of 1156. 12V, 21W. | 199 |
| ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 21W. | 1156 |
| ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base. Variant of 1157. 12V, 21/5W. | 1034 |
| ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Lower wattage variant of 1156. 12V, 13W. | 1073 |