The Aeroflow Performance Billet GM LS rocker arm mounting stands mount between the shaft and cylinder head for the correct rocker arm mounting position. These are constructed from 7075 billet aluminium to ensure longevity,while also reinforcing them for more rigidity in high-horsepower and boosted applications. These bars are designed to help with rocker arm control and cut back on flex and distortion that is imposed from the valvetrain. Bars will fit stock and aftermarket LS3 heads but if these are used on an OEM cylinder heads not all castingare the same and they may require some slight modifications. When installingthese ensure to check rocker geometry and pushrod length.