Fox is what Ford named the chassis the car was built on. It actually started in 1978 with the Fairmont/Zephyr nameplates and was the first RWD Ford to use struts instead of shocks/upper control arms up front.
Here's a quick list of Fox platform cars (helpful when you're at the j/y looking for parts.
All Ford Fairmonts, and Mercury Zephyrs
Mercury Capri 79-86 (IMO The RS is the best looking Fox car ever made)
Ford LTD II & 79/80 and later Mercury Monarch
80-88 Ford Thunderbird, Mercury Cougar, Lincoln Mark series
The '94-2004 Mustangs were on the SN95 platform, basically an improved Fox platform.
2005 was the dawn of the S197 platform. Nothing radically different, but an improvement on the SN95.
I've liked them since they first came out. Coming from a family that had a '71 Mach I in the driveway, I was disappointed in the 74-78 cars, even the King Cobras. In the crowd I hung out with, Mustang II's (a.k.a. Mustang Too

)were what Street Rodders were parting out for the front suspensions.
The one that really struck a nerve and to this day I regret not buying was an '86 Capri RS 5.0 5spd. , Bubble hatch, spoiler, factory hood scoop, front air dam and the Marchal fog lamps. Sex on wheels.