All 2015 (and some 2014 4x4 and early 2016) Silverado/Sierra's come with one of two spindle types. You need to check which kind you have to ensure you get the correct products. Its easy to choose! Just locate your spindle and put a magnet to it. (see chart below) If the magnet sticks to the spindle, you know you have a cast iron spindle. If the magnet does not stick you need the cast aluminum. These two spindle's have different size ball joints, and this will determine which arms you will need.