Chevy Gen III LS Series Small Block (2003 & earlier), 4 short, 16 long, Black Oxide Finish, 12-Point Nuts
 
ARP High Performance series head bolt kits are tough. They are rated at 180,000 psi--15 percent stronger than Grade 8 fasteners. They come available with a reduced wrenching hex head or 12-point head that help eliminate the need for valvetrain removal when re-torquing cylinder heads.