All rocker designs are not the same-even if they are the same ratio. Both of these rockers have the same ratio. The steel unit (right) has contact points that are farther outboard from the pivot point. If you are having problems with the rocker contacting the spring retainer when the valve is closed, you may need to consider your rocker design. On our engine, the aluminum rocker on the left was allowing the pushrod to contact the guide plates; the steel rocker fixed that.