* 4.6L Modular V8: This was the most common engine. There were variations within this engine, with different horsepower ratings depending on the specific model (GT, etc.).
* 3.8L V6: This was a smaller, less powerful, but more fuel-efficient option.
Therefore, you need to specify the *trim level* (GT, LX, etc.) of the 1998 Mustang to know the *exact* engine.