When installing headers you will need header bolts, factory exhaust manifold bolts won't work. These Mr. Gasket Header Bolts are Grade 5 for strength, black oxide coated, and have a compact hex head that is ideal for use where space is minimal - your typical header flanges. Sold as a set of 12. Fits: AMC 290-401 Chevy Small Block 262-400 Chrysler Big Block 383-440 (Does not Fit 426 Hemi) Pontiac 326-455 Oldsmobile 330-455