Crucial safety information about bolts for body lift kits.
There are a couple of simple rules about using bolts and other fasteners for body lifts. Firstly regulations state that any modified component is at least as strong as the factory-fitted part. So if the manufacturer specifies a mild steel bolt (say 4.8 grade) and you select a high grade like 8.8, you will be perfectly safe if the nuts you choose have an interference fit to ensure they can't come loose.