I had the 6.4, totally different beast than the 6.7 I know, but went through 3 motors in less than 55000 miles.:M I too am convinced it was the cp4 hpfp that ate them up. Always an injector failure either flooding or depriving a cylinder causing the catastrophic failure. My service records,(oil changes religiously 3500 and fuel filters every other oil change) and draining of the water fuel separator monthly was/were impeccable. I went through the nail biting of worrying about Ford dissecting and possibly denying warranty due to water in that system. No rust, but pitting in mine... Wasn't until 3rd motor that they did a complete replacement of fuel system including rails and tank flush. Warranty paid all expenses, thank God it was under mileage limit for warranty! Who can afford 10-12K repairs? I hope the 6.7 PSD doesn't fail like the International 6.4 did. I looked at the 6.7's and drove many. Amazing truck! Just couldn't do it though... Flame me now and throw the grenades, but I went with Ram that has the cp3... Hope she lasts... Good luck