The Ford E-350 front side marker uses a 194 bulb size, while rear side markers accommodate either 3357 or 194 bulb sizes. The replacement chart covers 1975 through 1998 model 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 Ford E-350 front side marker position uses the 194 bulb across all listed model years from 1975-1998.
The 194 is a miniature wedge bulb operating at 12 volts and 3.78 watts, classified under the T10 form factor and recognized by the ANSI standard in both the United States and Canada.
The Ford E-350 rear side marker position uses the 194 bulb from 1975-1991, then transitions to the 3357 bulb for 1992-1998.
The 3357 is a single-filament wedge bulb operating at 12 volts and 27 watts, classified under the T25 form factor and also recognized by the ANSI standard in both the United States and Canada.
The 3357 draws significantly more wattage than the 194, meaning the two bulb types are not interchangeable despite both using wedge-base construction.
For 1992-1998 E-350 models, the front and rear side marker positions require different bulb types, with the front taking the lower-wattage 194 and the rear taking the higher-wattage 3357.
For 1975-1991 E-350 models, both the front and rear side marker positions share the same 194 bulb specification.