The fuel filter on a 1999 Chevy S-10 is typically located
on the frame rail, near the fuel tank, on the passenger side of the vehicle. However, the exact location can vary slightly depending on the engine and specific trim level. It's often found within easy reach, but may require some maneuvering to access. You'll likely need to look underneath the truck.
Before working on it, always disconnect the negative battery terminal to prevent sparks. Also, be aware that fuel is flammable and work in a well-ventilated area.