Mercedes-Benz 380SEC front side marker bulbs use P21/5W size while rear side marker bulbs use 3893 size. The replacement chart covers 1982 to 1983 vehicle 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 380SEC uses two distinct bulb standards across its front and rear side marker positions, with the front position specifying a P21/5W and the rear position specifying a 3893 for both 1982-1983 model years.
The P21/5W is an ECE-standard bulb intended for European and worldwide markets, operating at 12V with a dual-filament configuration rated at 21W and 5W respectively.
The dual-filament design of the P21/5W allows a single bulb to serve two lighting functions simultaneously, with the higher 21W filament typically handling braking or turn signals and the lower 5W filament handling position or running light duties.
The P21/5W uses a BAY15d bayonet base, a two-pin offset base type where the two pins are positioned at different heights to prevent incorrect installation orientation.
The 3893 is an ANSI-standard bulb designated for the US and Canadian markets, also operating at 12V with a dual-filament configuration and sharing the BAY15d bayonet base with the P21/5W.
Although the P21/5W and 3893 share the same BAY15d base type, they originate from different regional standards, ECE and ANSI respectively, and are classified under specialty application use for the 3893, which indicates these two bulbs are not confirmed interchangeable despite the shared base.