Lincoln Mark VIII front turn signal bulbs use 3457NA or 3357NA size, while rear turn signal bulbs use 3357 size. The replacement chart covers 1993 to 1998 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 Lincoln Mark VIII front turn signal uses the 3357NA bulb for model years 1993-1996 and transitions to the 3457NA for 1997-1998.
The 3357NA is a single-filament T25 wedge bulb rated at 12V and 27W, featuring natural amber glass that produces an amber signal color without the need for an amber-tinted lens.
The 3457NA is a dual-filament T25 wedge bulb rated at 12V with a 27W main filament and a 7W secondary filament, also featuring natural amber glass.
The dual-filament design of the 3457NA means the front turn signal housing on 1997-1998 Lincoln Mark VIII models is wired to support two separate circuits, distinguishing it from the single-filament application used in earlier model years.
Substituting a 3357NA for a 3457NA in a 1997-1998 Lincoln Mark VIII front turn signal position would result in a non-functional secondary filament circuit, as the single-filament bulb cannot serve both electrical contacts.
The rear turn signal on the Lincoln Mark VIII uses the 3357 across all model years 1993-1998, indicating no change in rear turn signal bulb specification throughout the vehicle's production run.
The 3357 and 3357NA share the same T25 wedge form, single-filament design, 12V rating, and 27W output. The sole distinction is that the 3357NA incorporates natural amber glass while the 3357 does not.
All three bulb types in these specifications conform to ANSI standards applicable in both the United States and Canada.
Because the 3357 and 3357NA share the same T25 wedge base and electrical ratings, physical fitment in the rear turn signal socket is compatible between the two, though the amber tint characteristic differs.