Where is the fuel shutoff switch on a 1987 Chevy truck?

There isn't a readily accessible, easily located fuel shutoff switch on a 1987 Chevy truck as a standard feature. Unlike some later models or other vehicle makes, GM didn't include this as standard equipment on most of their trucks in that year. To shut off the fuel supply, you would typically need to disconnect the fuel pump's electrical connection or potentially deal with the fuel pump itself (though this is far more involved and not recommended unless you're experienced with auto repair).