If you are running an excess amount of boost in your 6.9L Ford Diesel engine, your stock head bolts are in serious danger of stretching, causing head gasket failure. ARP diesel head studs are good insurance against head gasket failure. Don't let a blown head gasket ruin your day at the track. It is for good reason that virtually every top professional engine builder relies on ARP Pro Series head studs for their all-out competition powerplants. Simply stated, there's not a better stud setup on the market today. ARP uses a premium grade 8740 alloy that is rated far superior to aircraft quality. Then, each stud is placed vertically in special racks and precisely heat-treated to 200,000 psi. ARP studs are thread rolled after heat-treat, which gives them about 1000% (that's ten times) better fatigue strength than those studs that are threaded prior to heat-treat (a very common industry practice). You wont find a better quality stud on the market from any other source. Comes with packet of assembly lubricant.