Where is the fuel filter located on a 1988 Chevy truck 350 4x4?

This will depend on your carburetor type. On a 1984 Chevy 4x4 with a 4 Barrel carb, the gas line comes up to the front of the carb (side towards the front of the truck) and there is a 5/8" fitting connected to a 1" fitting. On the 5/8" fitting there is a metal tube running through the middle. When the enging is cool unscrew the 5/8 fitting first and move it aside and then unscrew the 1" fitting and remove. When you remove it you will find the fuel filter typically 3/4" in diameter by 2" in length. One end will have an opening with a gasket on it and the other end will be closed. Pay attention to this when installing the new filter. The closed end goes in first. Reverse procedure to install the filter and fittings.