Ferrari 348 GTB front and rear side marker bulbs utilize a 158 size bulb for both locations. The replacement chart covers 1993 to 1994 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 Ferrari 348 GTB uses the 158 bulb across all listed positions and model years, covering both front and rear side markers for 1993-1994.
The 158 is a miniature wedge-type bulb, classified under the T10 form factor, which refers to a tubular bulb approximately 10mm wide at its widest point.
The 158 operates at 12 volts and draws 3 watts, placing it in the low-wattage range typical of marker and indicator lighting rather than primary illumination.
The wedge base design means the 158 is held in its socket by the tension of the base itself rather than by a bayonet or screw mechanism, which is a common trait in small automotive marker bulbs.
The 158 carries an ANSI designation, meaning it conforms to a standardized specification recognized in both the United States and Canada.
Because the same bulb number applies to both the front and rear side marker positions on the Ferrari 348 GTB, the 158 serves as a single fitment solution for all four side marker sockets on the vehicle.
The T10 wedge format is widely used in automotive applications, and bulbs sharing this base type are physically interchangeable in terms of socket fit, though wattage and voltage ratings must still match the original specification for correct operation.