One of the first questions to arise after Ford officially confirmed that the 2015 F-150 would be going to an aluminum body is if its big brother Super Duty would follow suit. If this spy footage is to be believed, the answer is yes. The stealthy videographers took a magnet to the cladded testers to see if there was any attraction. The magnet was completely indifferent to the sheetmetal, indicating the material was indeed aluminum.
However, the rationale for utilizing aluminum on HD trucks is somewhat different than it is for ½-tons. Whereas light-duty trucks are subject to EPA testing and manufacturers’ Corporate Average Fuel Economy (CAFE) standards, HD trucks are exempt. So what would be the motivation for moving to aluminum on bigger trucks if they're not subject to fuel economy testing or averages? One word: capacity.
In both the form of payload and towing capacity, a lighter overall weight could potentially enable higher towing and payload capacities, a critical selling point and advantage in the HD market. Even with moving to aluminum, these trucks will still be massively heavy. However, an overall weight loss of 700-800 pounds could potentially give the new Super Duty a critical edge over its crosstown rivals in towing and payload capacity.