So this is actually kinda BS. The F-450 is considered F-series, but it's not really a consumer level vehicle the way an F-350, 250 or 150 is. So they can say highest F-series this and that but it's not quite that simple.
That's the 450. Not the 350 and especially not the 250, which is the most popular of the Super Duty lineup (obviously).On Monday it introduced its 2017 F-Series Super Duty which it says has both class-leading towing and payload specs. The max gooseneck capacity for the 2017 F-450 properly equipped is now 32,500 pounds, fifth wheel towing is 27,500 pounds, conventional towing is 21,000 pounds and the payload rating is now 7,630 pounds.
The Duramax is going to need an update if it wants to continue competing in the HP/torque wars, though. It is at the end of its architectural capability as far as I know at 397 hp and 765 lb-ft.