Mr Gasket Sure-Lock Rocker Arm Nuts, .540" Shank OD, 3/8" Stud Size, Gold Tone FMr Gasket Sure Lock Rocker Arm Nuts, . 540" Shank OD, 3 8" Stud Size, Gold Tone FinishSuit Small Block Chevy & Ford 289 351 (Except 351C) MG923 923 For aluminium rocker arms only. Designed to keep the rocker arms positively locked for precise and critical valve train adjustments. Manufactured from quality grade steel, then heat treated for extra strength and plated with a durable finish. Kits include 16 rocker arm nuts with socket head set screws and