Mercury Cyclone front side marker bulbs measure 161 or 194 in size, while rear side marker bulbs measure 97 or 194, with specifications varying by production year. The replacement chart covers 1970 to 1971 model years and details bulb sizes for each marker position.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 1970 Mercury Cyclone uses the same bulb, size 194, for both the front and rear side markers, meaning a single bulb type serves all four side marker positions that year.
The 194 is a T10 miniature wedge bulb rated at 12V and 3.78W, conforming to ANSI standards for the US and Canadian markets.
For 1971, the front and rear side markers require different bulb sizes, with the front using a 161 and the rear using a 97.
The 161 is also a T10 miniature wedge bulb but is rated at a lower 1W compared to the 3.78W of the 194, making the two bulbs electrically distinct despite sharing the same physical base type.
Because the 161 and 194 share the T10 wedge base, they are physically interchangeable in the socket, but their wattage difference means substituting one for the other would alter light output and could affect circuit load.
The 97 bulb used in the 1971 rear side marker positions carries a BA15s single-contact bayonet base and is rated at 12V and 13W, placing it in a significantly higher power class than either the 161 or the 194.
The 97 is described as a variant of the 1156 bulb family, which is a common single-filament automotive bulb, though the 97 and 1156 are not confirmed as direct drop-in replacements for one another without further verification.
The BA15s bayonet base of the 97 is physically incompatible with the T10 wedge sockets used by the 161 and 194, so no cross-substitution is possible between the 1971 rear marker bulb and the front marker bulb without a socket adapter.
All three bulb sizes, 161, 194, and 97, conform to ANSI standards applicable in both the United States and Canada.