* Near the fuel tank: This is the most common location. You'll likely have to get underneath the vehicle to find it.
* In the frame rail: Sometimes it's mounted to the frame rail, making access difficult.
Because of its often inconvenient location and the potential need for specialized tools, it's strongly recommended that you consult a repair manual specific to your 1984 Chevy S-10 Blazer and its engine type (e.g., 2.8L V6, 4.3L V6, etc.). A Haynes or Chilton manual will have diagrams and detailed instructions. These manuals are usually available at auto parts stores or online.
Simply searching online for "1984 Chevy S-10 Blazer fuel filter location [your engine size]" may also yield images or forum posts showing its location for someone with the same engine.
Caution: Working with fuel lines involves flammable materials. Take appropriate safety precautions, including disconnecting the battery's negative terminal before starting work.