Mercedes-Benz G550 front side marker bulb size is 3893, while rear side marker bulbs measure 12821 and 3893. Replacement chart covers 2009 to 2018 production years with bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercedes-Benz G550 uses two distinct bulb types across its side marker positions: the 3893 and the 12821, each with different base types and electrical characteristics.
The 3893 is an ANSI-standardized bulb rated at 12V, featuring a BAY15d bayonet base and a dual-filament construction, classifying it as a specialty application bulb.
The 12821 is a Philips part number designating a miniature wedge bulb in the T10 form factor, rated at 12V and 5W, with a W2.1x9.5d wedge base.
The BAY15d base of the 3893 and the W2.1x9.5d wedge base of the 12821 are physically incompatible with each other, meaning the two bulb types are not interchangeable between sockets.
The front side marker position on the G550 uses the 3893 bulb across all model years from 2009-2018.
The rear side marker position on the G550 (Mercedes-Benz G550) uses the 3893 bulb for the 2009-2010 model years, then transitions to the 12821 for the 2011-2018 model years.
Because the front and rear side marker sockets accept different bulb types on 2011-2018 models, a single bulb part number does not satisfy both positions simultaneously.
The dual-filament design of the 3893 means it contains two separate filaments within one envelope, a characteristic absent from the single-filament 12821 wedge bulb.
The 3893 carries ANSI standardization recognized in both the United States and Canada, indicating conformance to a defined performance and dimensional specification within those markets.
On 2009-2010 models, both the front and rear side marker positions share the 3893 bulb, making a single part number applicable to all four side marker sockets for those years.