The Fuel Filter P/N 100523 is located inside the left rear "leg" of the frame, near the transmission. It is mounted by a circular bracket that encloses the filter and is in turn bolted to the frame rail with two M6 bolts and lock nuts. The tightness of the bracket is adjusted by an M4 through-bolt and nylock nut. A new filter is included with the fuel pump kits. The new filter will include new copper or aluminum sealing rings. Some cars will use one sealing ring on the banjo fitting connection toward the engine, some will use two. The bottom (inlet) fitting is a pipe thread with no seal. Replace what you remove.
NOTE there is a second fuel filter inside the fuel tank. In the OEM style pump the filter screen P/N101643 is located at the center of the baffle at the bottom of the pickup hose. In the new Integrated Pump Assembly the in-tank filter P/N 107643 is attached to the bottom of the pump, also inside the baffle. Both are replaceable as separate components.
To replace the external filter, first break the compression connection at the inlet [bottom]. This may be difficult due to the age and all-steel construction of the fitting, but be careful not to damage the hard line as replacement is extremely difficult.
Release the filter and bracket from the frame rail, by removing the two M6 bolts. You may have to remove the LH air deflector to get to the nuts. With the filter now only held by the banjo fitting on the top, take the hollow bolt out of the top of the filter using the two-wrench method. Take the bracket from the old filter and install it on to the new filter, replacing the pad, with the screw just tight enough so that the filter will barely spin in the clamp. Move the inlet 90 degree fitting to the new filter. You may use Teflon tape on the threads into the bottom of the filter only if you like, just be sure that it doesn't block the flow. Do not use tape on compression or banjo fittings.
Re-connect the banjo fitting on top. Position the fitting so that when it is tightened down, it points 180 degrees away from the direction the inlet fitting is pointing. Rotate the clamp so that the filter mounts against the frame with both fittings pointing roughly parallel to the rail. Install the two mounting bolts. Connect the inlet to the bottom fitting and tighten firmly. Tighten the bracket through-bolt so that the filter is held securely by the clamp.
Run the car, stop and then check for leaks immediately AND after a 10-15 minute period of time has passed.
Updated DAS [minor edits] 6/22/2016