The Mercedes-Benz 250SL uses a 3893 bulb size for both front and rear side marker applications. The replacement chart covers 1966 to 1968 production years with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 3893 bulb is the sole bulb type specified across all side marker positions on the Mercedes-Benz 250SL, covering both front and rear applications for the 1966-1968 model years.
The 3893 is a dual-filament bulb, meaning it contains two separate filaments within a single envelope, allowing it to serve more than one lighting function from a single unit.
The 3893 operates at 12 volts, consistent with the standard automotive electrical systems of that era.
The 3893 uses a BAY15d bayonet base, which is an offset twin-pin bayonet mount. The offset pin placement is a deliberate design feature that prevents incorrect insertion, as reversing the base would connect the filaments to the wrong circuits.
The 3893 carries an ANSI designation, indicating it conforms to a standardized specification recognized in the United States and Canada.
The 3893 is classified as a specialty application bulb, distinguishing it from general-service automotive bulbs and indicating it is intended for specific fitment contexts rather than broad interchangeable use.
The front and rear side marker positions on the 250SL share an identical bulb specification, meaning the 3893 is used uniformly across all four side marker locations on the vehicle.
Because the BAY15d base relies on physical pin offset to enforce correct orientation, substituting a single-filament bulb or a bulb with a symmetrical base would represent an incompatible fitment regardless of voltage or size similarity.