Well, if it is a gasoline engine then there is no serviceable filter. However there is actually one that is built into the fuel pump/module assy. (Inside the fuel tank). It is meant to be a lifetime filter.
If it is a diesel that is a different story. It is located on the pass. side of the engine near the A/C accumulator ( The large aluminum cylinder bolted to the firewall )
frame rail
The 1986 Chevrolet C10 pickup truck fuel filter is located inside of the fuel tank. The fuel tank will need to be removed in order to change the fuel filter.
it is located on the inside of the frame rail on the drivers side.
The 98 models did not have a cabin air filter.
basic tune up specs are found on the emissions label located on the air filter housing
The C2500 is 2wd and k2500 is 4wd.
under neath the truck
on frame rail under driver side doorunder truck
Should be along the fuel line somewhere in front of the gas tank.
Slide in under the truck behind the drivers door and look up in the frame rail and you will see it.
Chevrolet K series answer C designates 2WD as in C1500 = 2WD 1/2 ton K designates 4WD as in K2500 = 4WD 3/4 ton -tweek
You turn it counter clockwise!