Ford's 2016 F-Series Super Duty in full disguise, although some changes can be seen on this version.

Almost lost in the fanfare surrounding the debut of the all-new, “aluminum-intensive” 2015 Ford F-150 has been the fate of the Super Duty models to follow. While the light-duty F-150 may make up the majority of the sales, the heftier F-250, F-350 and even bigger trucks have a significant following, as well, and appeal to buyers who make some tough demands.

No surprise, then, that Ford is taking a little longer to roll out their replacements. But if anyone is still wondering, they, too, will migrate from steel to aluminum when they make it to market for the 2016 model-year.

A closer look at these photos of the 2016 F-250 prototypes shows some major (how major can you get in a pickup’s design?) changes are coming in the big boys from Ford. For one, the grille is more detailed in appearance with multiple horizontal bars above and below the centered Blue Oval icon. At the bottom is a redesigned – flattop – bumper and square corner air deflector.

A second major change is the shape – the rake, or slope – of the windshield, all the better for the smoother flow of air over the body and a tiny improvement in fuel economy. Check out the door handles, horizontal, pull-type (?) vs. the vertical finger pulls of current models.

Looking at the 2016 F-250 prototype shows some changes. The grille is more detailed with multiple horizontal bars above and below the Blue Oval.

Unchanged are the side mirrors, still the oversize types that Ford evidently thinks big truckers require for their oversize rigs. Is that rumpled camo an indicator of extendable mirror positioning?

What we can’t see is the amount of aluminum that Ford plans for its bigger F- series models. We couldn’t get close enough to the prototypes to conduct a “magnet test” on parts of the body where the lighter material will be used. But insiders indicate that all F-Series models, from the bottom to the top of the line-up, will make extensive use of the lightweight metal going forward.

Now, how do we know that these protos are the larger F-series Fords for 2016, not prototypes of the current F-150 models? Those eight-lug wheels are dead giveaways, as blatant as the oversize mirrors and horizontal door handles.

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Inside, the new Super Duty models will follow the lead of the F-150, offering buyers more refinement – with soft touch and more elegant materials, as well as more functionality. Look for more storage niches, more plugs and outlets. There will be a tilt/telescope wheel, according to sources, parking sensors, the latest-generation Sync infotainment system, and more.

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The F-250 is expected to offer at least two engine packages, including a 6.2-liter V-8 making 385 horsepower and 405 pound-feet of torque. The 6.7-liter PowerStroke diesel will boost those numbers to 440 hp and a whopping 860 lb-ft of stump-pulling torque.

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Ford isn’t talking much about details, but if the F-150 is any indication, it will try to strike a balance with the Super Duty models, using the lighter weight of the new models to help it deliver a bit better mileage as well as improved cargo and towing capacities.

(Paul A. Eisenstein contributed to this report.)