The Mercedes-Benz 560SL uses a 3893 bulb size for front side markers and a 12821 bulb size for rear side markers. The replacement chart covers 1986 to 1989 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 Mercedes-Benz 560SL uses two distinct bulb types across its side marker positions, with the front and rear positions requiring different bulbs throughout the 1986-1989 model years.
The front side marker position on the 560SL calls for the 3893 bulb across all four model years covered by the specifications.
The 3893 is an ANSI-standardized bulb recognized in both the United States and Canada, operating on a 12-volt system with a BAY15d bayonet base and a dual-filament design.
A dual-filament construction in the 3893 means the bulb contains two separate filaments within a single envelope, a configuration typically associated with functions requiring two brightness levels, such as combined running and turn signal duties.
The BAY15d base type features two offset pins on a bayonet mount, a design that physically prevents incorrect single-filament substitutes from seating properly, making base type a critical fitment factor.
The rear side marker position on the 560SL uses the 12821 bulb, a Philips part number, across the same 1986-1989 span.
The 12821 is a T10 miniature wedge bulb with a W2.1x9.5d base, rated at 12 volts and 5 watts, representing a single-filament design that is not interchangeable with the dual-filament 3893 used at the front.
The wedge base of the 12821 relies on the tension of its wire leads rather than a locking mechanism to hold it in the socket, a construction that differs fundamentally from the bayonet base of the 3893.
Because the 3893 and 12821 use entirely different base types, bayonet versus wedge, neither bulb is physically compatible with the socket intended for the other, and substitution between the two positions is not possible.
The 12821 designation is a Philips-specific part number rather than an ANSI industry standard, meaning equivalent bulbs from other manufacturers may be sold under different numeric designations while sharing the same T10 wedge form and 5-watt rating.