M-6014-Z304 Use when installing M-6049-Z304/Z304A/ Z304D/Z304DA heads on a 351W block .500" diameter studs with 12 point nuts and hardened washersM-6014-Z304 Use when installing M-6049-Z304/Z304A/ Z304D/Z304DA heads on a 351W block .500" diameter studs with 12 point nuts and hardened washers.