Doesn't exist. The car was modified with either a 2.3 turbo swap, or someone bolted a turbo onto the existing motor. No 93 Mustangs came with a turbo. Just a naturally-aspirated 4-cylinder, and V8. The only other Mustangs from the period you described that came with turbos are the 83-84 Mustang GT Turbos (very rare). Having said that, I can't say what the car you are currently looking at is worth, especially without knowing the overall condition of the car. Good luck with the sale! If the modification was done properly, and the car is in decent running condition, it should be very fun to drive.