GMC M300 Brake Bulb Size
The GMC M300 brake light requires bulb size 1073 or 1129 depending on the specific vehicle configuration. Data for 1129 and 1073 bulbs covers the range from 1954 to 1957.
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 |
|---|---|
| 1956-1957 | 1073 |
| 1954-1955 | 1129 |
Bulb Specifications
| Description | Bulb Size |
|---|---|
| ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Lower wattage variant of 1156. 12V, 13W. | 1073 |
| ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base. Variant of 1157. 12V, 21/5W. | 1129 |