I have no idea how popular or not such a car would be.
A Mustang is a Mustang only if it's a Mustang. Verifying a Mustang is a Mustang is very easy.
1. Ford 2.Various badging, pony, 289, tri-bar, 5.0 , DH, GT500 etc.
3. 2-doors
4. 4-doors (if checked end verification and notify owner they have something just not a Mustang.