Well, it may or may not be practical, but would surely be a fun project someone with the
right tools, skills, patience, and desire, and a fair amount of spare money probably wouldn't hurt either

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I'm not that familiar with the '06's, but on my '011, i'm reasonably certain that this would require some higher-level know-how to accomplish, considering how closely integrated the headlight, fog lights, ect are within the bumper assembly.
And I remember a few months ago, after a low-speed meeting with a solid steel guard rail, I had to replace the lower part of the bumper that wraps around the bottom & sides, the body shop found some other parts behind the plastic/rubber that needed to be replaced too, most of which were of the steel variety, and this nearly doubled the cost of the work....
Therefore, one thing that you may want to look at beforehand is the weight difference between the plastic/rubber parts & the steel replacements, as this could possibly effect the handling, ride, and wear & tear on the front suspension parts...as those old steel bumpers, especially from F150's, are pretty friggin heavy...
Good luck, and please post pics should you decide to move forward with this project
