On a 1999 Chevy Silverado with a 5.3L engine, the fuel filter is located
on the frame rail, near the fuel tank, on the passenger side of the vehicle. It's usually fairly close to the rear axle. You'll likely see fuel lines connected to it. It's often a cylindrical canister.
However, because of slight variations depending on trim and options, it's best to consult a repair manual specific to your year and model Silverado. A picture in the manual will give you the most precise location. You can find these manuals online or at auto parts stores.
