Mack U Courtesy Bulb Size
The Mack U courtesy light utilizes 912 and 1003 bulb sizes depending on the specific configuration of the vehicle lighting system. Data for the lighting components spans from 1981 through 1989 for the listed truck series.
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 |
|---|---|
| 1989 | 1003 |
| 1988 | 912 |
| 1985-1987 | 1003 |
| 1984 | 912 |
| 1982-1983 | 1003 |
| 1981 | 912 |
Bulb Specifications
| Description | Bulb Size |
|---|---|
| ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 21W. | 1003 |
| ANSI standard (US & Canada). Wedge bulb (T15). Variant of 921. 12V, 12W. | 912 |