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 66-00 cylinder heads and install 99156-16 3/8" rocker arm studs and 36650-1 pushrod guideplates (heat treated pushrods required), or use 36655-16 Conversion Kit (no machining required) on 77-00 pedestal mount cylinder heads for street applications. 11747-16 - Must machine 66-00 cylinder heads and install 99157-16 7/16' rocker arm studs and 36650-1 pushrod guideplates (heat treated pushrods required). 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 5/16" Pushrod Guideplates Set/8 36650-1$36.60 Pushrod Guideplate Conversion Kit 36655-16$120.00