The Mercedes-Benz SLK320 tail light utilizes bulb size 67 and bulb size 12821 for the lighting components. Data for the specified vehicle covers the range from 2001 through 2004.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercedes-Benz SLK320 outer tail light draws from four distinct bulb types across its production years: the 12961, 1156, 67, and 12821.
The 1156 and 67 are both ANSI-standard single-filament bulbs sharing the BA15s bayonet base, making them physically interchangeable in terms of socket fit. However, the 1156 operates at 21W while the 67 operates at 8W, meaning the two are not electrically equivalent and serve different lighting functions despite their shared base type.
The 12961 and 12821 are both Philips part numbers designating miniature wedge bulbs of the T10 type with a W2.1x9.5d base, rated at 12V and 5W. These two bulbs share identical electrical and physical characteristics.
For the 2003 model year, the SLK320 outer tail light uses a 1156 in one position and a 12821 in a second position, combining a high-wattage bayonet bulb with a low-wattage wedge bulb within the same assembly.
The 2004 model year shifts the first position from the 1156 to the 12961, while the second position changes from the 12821 to the 67. Both substitutions replace a wedge-type bulb or a high-wattage bayonet bulb with alternatives of differing base types or wattages.
The 2001-2002 model years share the 12821 in the second position, though the first position differs, with 2001 using the 1156 and 2002 using the 12961.
Because the 1156 and 12961 occupy the same positional slot across different years yet use entirely different base types (BA15s bayonet versus W2.1x9.5d wedge), these bulbs are not interchangeable, and year-specific fitment is a relevant factor when sourcing replacements for the SLK320.