For first time repairs. 3/8-16 starter bolt repair kit includes all the tools and 4 special inserts with straight section p/n 153501 for bolt alignment built into the insert. The stripped Starter bolt thread depth of the hole should be 1.200" inches or 30mm Depth minimum. Note: This kit can also repair a failed coil style insert. The failed hole should not be larger than the drill included in kit which is .484 inches  Instructions