The Mercedes-Benz 300SDL front side marker bulb uses a P21/5W size, while the rear side marker bulb uses either 232 or 5008 size. The replacement chart covers 1986 to 1987 model 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 300SDL uses the P21/5W bulb for the front side marker position across both 1986 and 1987 model years.
The P21/5W is an ECE-standard dual-filament bulb rated at 12V with a 21W main filament and a 5W secondary filament, mounted on a BAY15d bayonet base. The dual-filament design allows a single bulb to serve two lighting functions simultaneously.
The BAY15d base features two pins offset at different heights, which prevents incorrect installation by ensuring the bulb can only be seated in one orientation.
The rear side marker position of the 300SDL differs between the two model years, with the 1987 model using a 232 bulb and the 1986 model using a 5008 bulb.
The 232 is an ANSI-standard festoon bulb rated at 12V and 3W, fitted with an SV8.5 base. Festoon bulbs are cylindrical in form and make contact at both ends rather than through a base pin or bayonet fitting.
The 5008 is an ANSI-standard single-filament bulb with a BA15s bayonet base, rated at 12V and described as a lower wattage variant of the 1156. The BA15s base uses a single pin, distinguishing it from the dual-pin BAY15d used by the P21/5W.
Because the 232 and 5008 differ in both base type and physical form, they are not interchangeable with each other despite occupying the same rear side marker position across the two model years.
The P21/5W and 5008 share a bayonet-style mounting system but use different base configurations, making them incompatible with each other's sockets.