Amongst these are several special tools which are required to remove and install the fuel injectors and therefore, it is advised that such tools together with any other related ones be sourced in advance before attempting to undertake the exercise. For 7.3L engines, start at the valve cover and remove it and unplug the electrical connector from the fuel injector. Blank off all cross passage and oil rail drain plugs inside the engine head so the oil can drain into the galleys; not doing so causes hydrostatic lock and extensive damages to the engine. Remove the drain plugs at the rear of each cylinder head to drain the diesel fuel and remove the retaining screws and oil deflectors from each fuel injector hold-down plate, then unbolt the outboard injector retaining bolt and remove the injector with care so that copper washer and possibly any O-ring material is retrieved. Label the injectors so that they will not be mix up, put the caps on the ends and place them in a holder which will help keep them clean. In general, the injector sleeves do not have to be withdrawn, but if they have to be withdrawn, it must be done differently, and with special tools. Close the injector bores in the cylinder head to avoid the entry of debris. Valve covers must be removed and the high-pressure fuel rail must be unbolted for 6.0L and 6.4L engines but do not remove anything else from fuel rail. Subtract the block-to-head tubes from the oil rail assemblies; to push the injector wiring out of the rocker arm carrier, you have to use a special tool; also be extremely careful, as it is easy to lose small snap-rings in the oil drain holes near the injectors; in order to avoid this, it is necessary to stuff clean rags in these holes. And when the countering check on all the parts shows that none is missing, then go ahead with the installation in the same procedure as it is followed for 7.3L engine but before inserting the injector into the cylinder head, make sure the oil drain plug and fuel drain plug are fixed well firmly, then clean the sleeve of the injector, then make sure the O-rings, cushion rings, and copper gasket are new then only the Do not hit the injector to get it in place and be sure that all traces of the oil and fuel are washed off to prevent hydrostatic lock. For engines 6.0L/6.4L set new D-ring seals on every block-to-head tube, and let it to sit for some time to 'relax' before fitting of the part. Replace all worn O-rings and put a new copper washer, new clamps and nuts on each injector; make sure that the wiring does not obstruct other mechanisms. Grease the block-to-head tube and fit the seals then place the oil rail onto the injectors so that the lead angle mates well with the injectors. Install first a start bolts on each end of the manifold and one in the center of the rail and then tighten the bolts, align the oil rail over the fuel injectors and than install other bolts. Replace the guide studs with the original bolts, tighten all bolts to the correct torque indicated in the manual and in the precise sequence and connect the wiring of the injectors, finally and replace the valve covers in the reverse order of their removal.