Our ARP Flexplate to crank bolt kits are the strongest bolts you can get to attach a 6 bolt crank to flexplate for high horsepower and/or highly stressed applications. Made from 200,000 PSI forged aerospace alloy, these were originally developed for NASCAR winston cup competition. The bolts are fully heat treated prior to thread rolling and machining. Flat 12pt head design ensures no clearance problems during installation. These will also work for attaching the flexplate to the torque converter with Hemi or aftermarket racing torque converters that have 7/16" bolt holes (only 4 are required for this application, so you will have a couple spares.) If you have a stroker engine with aftermarket components, high stall, etc... these are must have item. You simply can not put in stronger bolts than these.