The Lincoln Mark IV front side marker bulb uses a 194 size, while rear side marker applications accommodate either 168 or 194 bulb sizes. The replacement chart covers 1972 to 1976 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 IV uses the 194 bulb for the front side marker across all model years covered, spanning 1972-1976.
The 194 is an ANSI-standard miniature wedge bulb in the T10 form factor, rated at 12V and 3.78W.
The 168 is also an ANSI-standard miniature wedge bulb in the T10 form factor, rated at 12V and 4.9W, making it a higher-wattage variant within the same physical family as the 194.
Although the 194 and 168 share the T10 wedge form factor, their wattage ratings differ, and the two are not interchangeable without accounting for that electrical difference.
The rear side marker on the Lincoln Mark IV uses the 194 bulb for 1972-1973 and transitions to the 168 bulb for 1974-1976.
The 1972-1973 Mark IV therefore uses the same 194 bulb for both front and rear side markers, while the 1974-1976 models require two distinct bulb types depending on position.