Our computer designed upper a-arm uses a fabricated, Boxed Arm design for ultimate strength. It allows significantly more wheel travel over stock when paired with an extended length, bolt in, aftermarket shock and we've built more caster into all of our Upper arms to give your truck the on road stability needed anytime a truck is lifted from its factory ride height. We use Trophy Truck grade uniballs to replace the weak, stock ball joints, giving you maximum articulation and performance in the dirt with your 2WD or 4WD Silverado. These will also work great with your existing lift kit that most likely has maxed out the stock ball joint angle. (Rear kits available too).