Unfortunately, on a 4WD F150, you'd also need a matching set of front gears, and if your truck has a decent amount of miles on it, you'd also likely need master install kits for both the front and rear to top it off. Frankly, going from 3.55 gears to 3.73 gears is not really a cost-effective way to regain lost power on the EcoBoost F150s. Your better bet would be a custom tune to get your truck more power and revise your F150's shift points to better handle the larger wheel and tire combination. While you could absolutely do gears, you're talking about a $1200 upgrade before install, while tuners with custom tunes can be had for much less.