Um 7.3 and 6.0 powerstroke are international. Also ford puts the 5.9 in their 650 and 750 trucks must be good enough for their big trucks. Ford owns the rights to Cummins yes but have made a lot of money off the Cummins and international gave them a hell of a deal on motors which the sold the Cummins for more per engine than what they paid for the international so they made out like bandits. Everyone from where I'm from has Cummins or duramaxs. I have 2 5.9s and have had no problems with them even after I've modded them