Mack RL Courtesy Bulb Size
The Mack RL courtesy bulb uses 2 distinct sizes: 912 and 1003, with each bulb size corresponding to specific vehicle configurations. The replacement chart covers vehicle production spanning 1981 to 1987.
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 |
|---|---|
| 1987 | 912 |
| 1985-1986 | 1003 |
| 1984 | 912 |
| 1983 | 1003 |
| 1981-1982 | 912 |
Bulb Specifications
| Description | Bulb Size |
|---|---|
| ANSI standard (US & Canada). Wedge bulb (T15). Variant of 921. 12V, 12W. | 912 |
| ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 21W. | 1003 |