Where is the fuel shut off switch on a 1998 Chevy Silverrado?

There's no easily accessible, single "fuel shut-off switch" like you might find on some older vehicles on a 1998 Chevy Silverado. Fuel delivery is controlled electronically. To stop fuel flow, you would need to disable the fuel pump (usually by disconnecting the electrical connection to it, which is a more involved process and generally not recommended unless you know what you're doing), or, in an emergency, disconnect the battery's negative terminal.

Disconnecting the fuel pump relay is another method, but locating that relay will require consulting your owner's manual or a wiring diagram specific to your truck's year and engine. This is also not a simple procedure for someone unfamiliar with vehicle mechanics.

Important Note: Tampering with the fuel system can be dangerous and should only be attempted by someone with experience working on vehicles. Improperly disconnecting components can cause damage or create a fire hazard.