Head Bolt Set, Hex Head AR134-3609Head Bolt Set, Hex Headfits GM LS Series (2003 & Earlier) AR134 3609 134 3609 High Performance Series hi gh Performance Head Bolts Are Available With A Reduced Wrenc hing Hex Or 12 point And Wide Area Flanged Head That Elimina tes The Need For Valve Train R emoval To Facilitate Cylinder Head Retorquing. All High Perf ormance Series Bolts Are 180,0 00 Psi (which Is 15% Stronger Than Grade 8) And Kits Come Co mplete With Hardened Parallel ground Washers.