Note: 1.6 ratio rocker arms. 11746-16 contains 3/8" adjusting nuts and 11747-16 contains 7/16" adjusting nuts. 11746-16 - Must machine 74-91 cylinder heads and install 99156-16 3/8"rocker arm studs and aftermarket pushrod guideplates. Special order heat treated pushrods are required for use with guideplates. 11747-16 - Must machine 66-91 cylinder heads and install 99157-16 7/16" rocker arm studs and aftermarket pushrod guideplates. Special order heat treated pushrods are required for use with guideplates. Street/Strip Rocker Arms 11746-16$251.20 Street/Strip Rocker Arms 11747-16$251.20 3/8" Rocker Arm Studs Set/16 See Product Info 99156-16$56.00 7/16" Rocker Arm Studs Set/16 See Product Info 99157-16$64.00