drqagrcr, I beg to disagree. It does not say after the "distribution block". What it says is "If brake system includes a differential pressure switch, line-loc on front brakes must have solenoid installed after the differential switch". My distribution block DOES NOT have a differential switch. I could replace the whole distribution block with a "T" for the front brakes and a pass-thru adapter for the rear and still have the same functionality.