baja bailey, are you retired from Ford ? Or do you have a brother sister mother father that is retired ? Just curious.
With your H2X (looked at your profile) either motor will blow your mind when compared to a gas motor. When people talk about walking another truck make sure you know all the facts about the trucks being compared. Axle ratios and "computer" modifications can make a significant difference in towing capability of any truck. With the weight you are talking about, you can easily get by with a 3:73 rather than a 4:10. This will help with highway speeds and fuel economy. You do not need to go with the 4:10 ratio until you get in the 9,000 - 10,000 lbs range.
The Duramax is built in the US. It is an Isuzu design and uses a Bosch fuel system.
The PowerStroke is built in the US, is designed and built by Navistar and uses a Caterpillar fuel system.
Another point to think about is the Powerstroke is actually a Navistar T444E. These engines are capable of substantialy higher power and torque and are limited in light duty truck applications. Next time you see a class 6 International truck look for the T444E on the side, its the same engine you'll find in the Ford.
Based on my experience to date, the Duramax is only used in light duty trucks. GM puts Cat diesels in their class 6 trucks. Would be interested if anyone has any other info. on this.
Again, not supporting one or the other, just passing on information.