Used on intake manifold & plenum 454/502 mag mpi engine gen vi. right-hand hexagon head style 18 thread quantity per inch screw (5/16-18 x 4 in.) unc thread series
Used on oil filter and adaptor 454/502 mag mpi engine gen vi. right-hand hexagon head style 18 thread quantity per inch screw (5/16-18 x 1/2 in) unc thread series
Used on closed cooling system 454/502 mag mpi engine gen vi. right-hand hexagon head style 16 thread quantity per inch screw (3/8-16 x 1 in) unc thread series