Wedge-Locking Header BoltsSmall Block Chevy, Big Block Mopar, AMC, Buick, Oldsmobile, & Pontiac 3/8" Diameter x 1" LongBlack Oxide12/pkg Fits: GM V6, SBC 265-400, Buick, Olds, Pontiac 79 & earlier, Mopar BB 383-440 exc 413, and AMC V8s with 3/8" boltsNote: 3/4" length bolts most often used for cast iron heads. 1" length bolts recommended for aluminum heads.