I was at the Navistar plant in Alabamaas a fleet customer watching the first 6.0L batch come off the line.which is why they ditched navistar and made their own decent powerplant...
Interesting that the Navistar crank wasn't balanced and polished, while the Ford crank was. It was odd to see the 2 cranks go down the line, looking so different. I asked the engineers why. Lower rpm limits on the Navistar was the answer.
Little did anyone know how bad the 6.0L and the VT365 for Navistar would be.