Mercedes-Benz 200D License Plate Bulb Size

The Mercedes-Benz 200D license plate light uses bulb sizes DE3423 and 12821 for the rear exterior illumination. Data for the specific components covers the time range from 1966 to 1973.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Bulb Size by Year Range

Years	Bulb Size
1968-1973	DE3423
1966-1967	12821

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Festoon bulb, 41mm length, end-cap contacts. 12V.	DE3423
Philips part number. Miniature wedge bulb (T10) with W2.1x9.5d base. 12V, 5W.	12821

Other Locations

Additional Notes

The Mercedes-Benz 200D license plate bulb specifications cover model years 1966-1973, with two distinct bulb types used across that span.
The DE3423 is an ANSI-standardized festoon bulb rated at 12V, measuring 41mm in length and making electrical contact through end-cap terminals rather than a wedge or pin base.
Festoon bulbs seat between two spring clips within a housing, which is a different mounting method than the wedge-style base found on the 12821.
The 12821 is a Philips part number designating a T10 miniature wedge bulb with a W2.1x9.5d base, rated at 12V and 5W.
The W2.1x9.5d base designation describes a wedge-type connector where the bulb is held in place by friction against the socket walls, with no separate metal base or cap.
The Mercedes-Benz 200D used the DE3423 festoon bulb for model years 1968-1973, representing the majority of the covered range.
Model years 1966-1967 used the 12821 wedge bulb, which has a physically incompatible base type relative to the DE3423 used in later years.
Because the DE3423 and 12821 use fundamentally different base configurations, one type cannot serve as a direct substitute for the other without a corresponding socket change.
The DE3423 conforms to ANSI standards applicable in the United States and Canada, meaning it meets a defined interchangeability specification rather than being tied to a single manufacturer.
The 12821 carries a manufacturer-specific part number from Philips, though other manufacturers produce electrically equivalent T10 wedge bulbs sharing the same W2.1x9.5d base standard.