[thackney]

The frame is still steel.

Aluminum Revolution: Ford introduces a new F-150
http://fuelfix.com/blog/2014/01/13/aluminum-revolution-ford-introduces-a-new-f-150/

Ninety-seven percent of the body of the 2015 F-150 is aluminum...

Some steel remains on the truck. The frame beneath it is built primarily of high-strength steel, which Ford says will make it tougher and stiffer than the current frame. There’s also steel in the front dashboard, because Ford thought steel was better at dampening nose from the engine.

[Spartan302]

I could have swore I heard somewhere Ford was going nearly all aluminum, it might be when the fuel mileage mandate rolls around in a few years?
Gonna get interesting when the Feds say everybody must get 50mpg or else.
may be the demise OF the big American pickup, might be a good time to get one before they are gone.
I have a choice, get another 3500HD with the natural gas option or get the Colorado, the NG sounds tempting, with an at home compressor station I can fuel it myself.

But of course the feds will want their road tax in some fashion.

[Smokin' Joe]

Some steel remains on the truck. The frame beneath it is built primarily of high-strength steel, which Ford says will make it tougher and stiffer than the current frame.

And in salty environments (Coasts, drilling rigs), cathodic corrosion will be interesting...