Gator Fasteners Heavy Duty Main Studs are design to hold the bottom end of your 24 Valve 5.9L together whether you’re building a tow rig, race truck or just a daily driver. *** Will not fit early 1997 and older trucks with 14mm studs. If your not sure, see the image showing the turbo oil drain ports. 14mm engines have one port while 12mm engines have two. • 2003-07 Common Rail Trucks will not be able to retain Factory Girdle/Block Stiffener with this kit. Description These fasteners have a much higher strength and will not stretch like the factory bolts will. The Gator Fasteners Performance Main Studs are a Heavy Duty studs designed for stock to built 5.9L Cummins engines. • For 24V Engines Only (for 12V engines, use MSK5912) • Not for trucks with Factory Girdle