Part# YT6305 - Yella Terra racing roller rockers, shaft type roller set to suit Rover 3.5 & 3.9 liter V8 engines. The ultimate race set up, proven over many years is this race series roller rocker gives you valve lash adjustment and minimal reciprocating weight in the strongest rocker arms available. Direct bolts on with no machining required ~ For use with mechanical or hydraulic camshafts. rocker arm ratio of 1.6 : 1, Total system includes cradles, shafts, rocker arms.