R3 race blocks are generally used in racing applications since some versions are designed for dry sump oiling systems, and some have shorter than stock deck heights. Some versions have the 48 degree tappet bores that must be used with racing cylinder heads. These blocks now come with dual motor mounts - both "LA" 318 and Magnum style motor mounts. The short deck versions of these blocks require a special timing cover (P4876631 or P4876632). These blocks are typically used in Late Models, 360 sprint cars, and drag racing