Ford Motor Company is going to start making its iconic F-150 truck out of aluminum to lose some 700 pounds of weight. It’s about mileage and increasingly tough efficiency standards. The niggling concern for buyers is the question of whether the aluminum truck will be as strong as the steel F-150s. It’s a big gamble because the F-150 is one of Ford’s biggest sellers and a profitable one too. Along with the aluminum makeover, the new F-150 also is getting a more muscular look, according to one Ford designer.