Just sold my fox 2 weeks ago.. Was thinking about going to a newer stang. I know just about nothing with these years. Are there certain issues with these cars? Is a higher mileage car a problem?
Check for water leakage from the cowl area into the car on the passenger side predominantly. This will show as soggy or water stained carpet padding and also more importantly corrosion in the electrical junction box behind the passenger side kick panel. If this junction box is corroded, it can cause all kinds of future electrical issues throughout the car.
If you're in love with the 05-09 body style, go with the newest model you can afford. Otherwise, I have a tough time recommending any 05-10 GT over an 11-up car. The coyote 5.0L is reason enough to buy one.