This head is identical to P/N 12363399, except it has 2.19" stainless steel intake valves, and 1.88" stainless steel exhaust valves with 11/32 stems. It also includes high performance valve springs, valve spring caps, keys and valve stem seals. These heads are designed for 396, 427, 454, and 502 engines. Technical Note: For 502ci engines, use head gasket kit P/N 12363411 and no sealant on the head bolt. For all big-block engines, use intake manifold gasket kit P/N 12366985, with intake bolt kit 12367959, and cylinder head bolt kit P/N 12367779.