The Porsche 911 front and rear side marker bulb sizes include 12961, 3893, and 97 specifications. The replacement chart covers vehicle production years spanning 1965 to 2008.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Porsche 911 front side marker positions across its model history draw from four distinct bulb types: the 12961, 3893, 97, and 12821, each representing a different base type and filament configuration.
The 12961 and 12821 are both Philips part numbers describing a T10 miniature wedge bulb with a W2.1x9.5d base rated at 12V and 5W. Despite sharing identical physical and electrical specifications, they carry separate part numbers and are listed for different model year ranges on the Porsche 911.
The front side marker on the Porsche 911 uses bulb 12821 for the 1965-1969 model years, transitions to bulb 97 for 1978, shifts to bulb 3893 for 1981-1998, and then moves to bulb 12961 for 1999-2008.
The rear side marker on the Porsche 911 follows a parallel but not identical pattern, using bulb 12821 for 1965-1969, bulb 97 for 1978, bulb 3893 for 1981-1993, and then bulb 12961 for 1994-1998.
The front and rear side marker positions diverge in their 3893-to-12961 transition year. The rear position transitions after 1993, while the front position retains the 3893 through 1998 before switching to the 12961.
The 3893 is an ANSI-standard dual-filament bulb with a BAY15d bayonet base, rated at 12V. A dual-filament design means the bulb contains two separate filaments within a single envelope, typically serving two independent lighting functions at different brightness levels.
The 97 is an ANSI-standard single-filament bulb with a BA15s bayonet base, rated at 12V and 13W. It is classified as a variant of the 1156 bulb family, which is a widely used automotive incandescent type. At 13W, it operates at a notably higher wattage than the 5W wedge bulbs used in other year ranges.
The BAY15d base of the 3893 and the BA15s base of the 97 are both bayonet-style fittings but are not interchangeable. The BAY15d base has offset pins to prevent incorrect installation of a single-filament bulb in a dual-filament socket, while the BA15s base has symmetrically placed pins suited to single-filament applications.
The W2.1x9.5d wedge base used by both the 12961 and 12821 is a push-in type that requires no locking mechanism, relying on the socket's spring tension to maintain contact. This base type is physically incompatible with the bayonet sockets used by the 3893 and 97.
Because the 3893 is a dual-filament bulb listed for a side marker position, substituting a single-filament replacement without confirming socket and circuit compatibility risks incorrect function, as the second filament circuit would remain unserved.