The Freightliner FS65 front turn signal uses a 1156 bulb size while the rear turn signal requires a 198 bulb size. The replacement chart covers vehicle production spanning 1996 to 2008 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 1156 bulb is the dominant type across the Freightliner FS65 turn signal specifications, appearing as the front turn signal bulb for every listed model year from 1996 through 2008.
The 1156 is a single-filament bulb rated at 12V and 21W, fitted with a BA15s bayonet base. The BA15s base uses a single contact pin offset to one side, which physically prevents incorrect installation of double-contact alternatives.
The 198 bulb is a T5 miniature wedge type rated at 12V and 2W, representing a significantly lower wattage output than the 1156. It is specified exclusively for the rear turn signal position on the Freightliner FS65 in the 1996-1997 model years under the Cab Over Engine configuration.
Both the 1156 and 198 bulbs carry ANSI standard designations valid across the United States and Canada, meaning their electrical and physical specifications conform to a standardized classification system shared between the two markets.
The 1996-1997 Freightliner FS65 entries carry a Cab Over Engine notation, indicating that these fitments apply specifically to that body configuration rather than to all variants of those model years.
The front turn signal position for 1996-1997 uses the 1156, while the rear turn signal for the same years uses the 198. These two positions require different bulb types and are not interchangeable with one another due to differences in base type, wattage, and physical form factor.
From 1998 onward through 2008, the rear turn signal position carries no listed specification, while the front turn signal retains the 1156 across all those years without a body configuration qualifier.