The Mercedes-Benz 300D uses a P21/5W bulb size for front side marker applications and either 232 or 5008 bulb sizes for rear side marker positions. The replacement chart covers 1975 through 1993 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 P21/5W is the most frequently specified bulb across the Mercedes-Benz 300D side marker data, appearing as the front side marker bulb for every listed model year from 1977 through 1993, with the exception of 1975 and 1976.
The P21/5W operates on an ECE standard and carries a dual-filament design rated at 12V with a 21W main filament and a 5W secondary filament, mounted on a BAY15d bayonet base.
The BAY15d base used by the P21/5W is an offset-pin bayonet fitting, which prevents incorrect single-filament bulbs from being seated in the same socket, making cross-substitution with single-filament types physically incompatible.
The 3893 is an ANSI-standard dual-filament bulb also using a BAY15d bayonet base, rated at 12V, and it serves as the front side marker for the 1975-1976 model years of the 300D.
Because both the P21/5W and the 3893 share the BAY15d bayonet base, physical fitment between the two types is possible, but their differing wattage ratings and regional standards mean they are not confirmed interchangeable replacements within these specifications.
The rear side marker position on the Mercedes-Benz 300D shows variation across three distinct bulb types depending on the model year, reflecting a greater degree of specification change at the rear than at the front.
The 3893 covers the rear side marker position for the 1975-1985 model years, while the 5008 applies to 1990-1992 and the 232 applies to 1987 and 1993.
The 5008 is a single-filament bulb using a BA15s bayonet base rated at 12V, described as a lower-wattage variant of the 1156 type. Its BA15s base is a single-contact fitting and is not interchangeable with the dual-filament BAY15d base used by the 3893.
The 232 is a festoon-type bulb with an SV8.5 base rated at 12V and 3W. Festoon bulbs are held in place by contact pressure at each end rather than by a bayonet or screw fitting, making the mounting mechanism entirely distinct from the other bulb types listed in these specifications.
The rear side marker position for 1987 and 1993 both specify the 232 festoon bulb, while the years immediately surrounding 1987 and the years 1990-1992 specify different types, indicating that the rear socket configuration was not uniform across the full production span covered by these specifications.