I've had my Ford 6.0 flushed along with the Cat C7. A Ford diesesl specialty shop flushed the truck and Freightliner flushed the Cat. They both insisted on using a special flushing chemical and then flushed it once more with distilled water to get the chemical out. The chemical was to remove any rust particles which flushing with just distilled water won't do.
Bill
Nodwell RN110 out moose hunting. 4-53 Detroit, Clark 5 spd, 40" wide tracks, 10:00x20 tires, 16,000# capacity, 22,000# weight. You know the mud is getting deep when it's coming in the doors.