Because the 302/351W water pump retaining bolts go through water passages, they'll get rusted and corroded over time, and then break off when trying to do service work to the water pump. This kit includes three of the longer bolts/studs that are the hardest to find, which are necessary for engines with A/C. Black oxide for corrosion resistance. Get these needed bolts beforehand to minimize downtime and make the job go more smoothly.