[ss3011]

The 8.1 has iron heads, and cast stainless steel exhaust manifolds. It also has mls exhaust gaskets, and special torque specs on the exhaust manifold bolts, and studs. GM put big money into that system to address warrantee problems with previous generation of Mark engines. My 1995 7.4 L had blown the exhaust gaskets, and sheared the bolts due to manifold expansion. I bought all the upgrade parts to fix it, and so far its worked well.