in addition to what everyone else said, looks for 8 of something under the hood like exhaust manifolds, COP, wires ect.
The GT also comes with foglights standard, as well as dual exhaust standard, but these are easily added.
But check the VIN number. But if you are this distrusting of the vehicle and the seller, i'd look elsewhere, i'd only buy from someone i'd trust
2007 Mustang GT Convertible Stage 0 E-Force #402 Supercharger, Brenspeed Tune (435/400), GT500 Fuel pump, Clutch Delete Option, Roush Front Fascia, Brembos, California Dream Hood, Qwitch latch flush mount hood pins, MRT Light Bar, J&M LCA's, BMR UCA, UPR catch can, 6000k, Pypes Bombs, Pypes X-pipe, Airbrushed Flame pieces under the hood, Clear corners, GT500 shocks , FRPP P-springs (rear), BMR Adj Panhard, E-Force engine covers
2012 Ford Focus SEL 5Dr with MyFordTouch, Auto-Park, 303A Package,