It's really the opposite with the Ford 450 pickup. They took a medium duty truck and slapped on a 14k GVW label.
Compared to Ford's 350 dually, which is equally beefy compared to a RAM 3500 dually, the F-450 does have the sharper turning wide front axle and 19.5" rims, along with 12-ply commercial tires that far outlast our 10-ply tires. But the Ford also has much larger brakes, and a significantly stronger rear axle.
You'll notice an F-450 pickup has less payload than an F-350 dually...and the reason is because the base truck weighs more.
Actually the F-450 is running the exact same moonbeam Dana m256 front axle as the F-350 drw except that it's a wide trac version and has a 7000lbs rating from ford vs a 6000lbs rating that the F-350 has.
The rear axle on both the F-450 and F-350 drw is the same Dana m300 except the F-450 has slightly bigger axle shafts that are needed to keep up the longevity to be on par with the F-350 (which is significantly less than the AAM axles that are on the Ram's) due to the heavier commercial tires, larger brakes, etc. There have been lots of rear diffs failing on the fords that hotshot whether that be 350's or 450's. The AAM's are much stouter, as well as the T-case and front end components.
The frame on the F-450 is the exact same as the F-350 and both have a different frame than the F-450 chassis cab. The F-450 has the same leaf spring pack as the F-350 drw and they are garbage compared to the Ram 3500 as the Ford's squat so badly even with 1500lbs of tongue weight. It's actually a joke how bad they squat. The 2017+ squat just as bad as they 11-16's.
So I disagree with the statement that they took a medium duty truck and slapped on a 14k rating. The specs state that they took a light duty truck and slapped on commercial tires/wheels, a wide trac front axle and bigger brakes. The Ram 3500 has stronger running gear and a better leaf spring pack with optional helper air bags from factory than an F-450.