Mack RM Back Up Light Bulb Size
The Mack RM back up light uses 1156 and P21W bulb sizes for the rear illumination system. Data for the lighting components covers the period from 1981 through 1993.
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 |
|---|---|---|---|
| 1981-1993 | 1156 | P21W | Check Price |
Bulb Specifications
| Description | Type | Shop |
|---|---|---|
| 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 |