I seriously can't believe i've never seen it done.
I've seen Ferrari brakes and rims on a Fox, but no AWD.
As for the truck thing...i used to bash those, but seriously if i were going to build a badass offroad toy and i had a clean Mustang body laying around, why not. If it's done right with some serious suspension work and not just a body thrown on a Bronco frame, i don't see why it's so stupid. There's plenty of badass street Mustangs.
If I lived in an area that needed a 4x4 for winter I would get one of thoes. Foxes are way more comfertable inside then an old Ranger or Bronco II. Plus it looks kinda neat. Got a nice ranger chasis laying around with a rotten body and a nice old 4cyl left for dead Fox body laying around go for it. better then going to the crusher