Fuel filter is located inside fuel tank. Is part of fuel sender assembly which consists of pump, regulator, fuel level sender and filter. You replace as a package. And a pricey one at that. I suppose one could drop the tank and remove/replumb the sender to eliminate the internal filter and install an external replaceable filter in the frame somewhere. Since our H3s have a returnless fuel system, meaning only a supply line to the fuel rail, the filter only filters what fuel the engine is actually consuming at the time. Older systems that utilize a regulator at the engine and a return line to the tank are constantly pumping fuel to the engine through the filter and back to tank . These systems have filters that are typically serviceable. Some of the older Dodge/Chrysler returnless systems had a large round air filter looking fuel filter attached to the bottom of the fuel pump assembly that were serviceable, but still required dropping tank to replace. At that point you might as well replace the whole assembly considering their failure rate at higher mileages IMHO. (Not picking on Dodges here, GM has had their problems with fuel pumps too. Have made a lot of money fixing both over the years.)