Yes they will bolt up ... as is bolt on. Depending on which size exhaust port on the SBC head you are installing them on, you most likely need to size the exhaust gasket for the head. I used regular Chevrolet " Rams Horn " exhaust manifolds on my D port shape aluminum ZZ4 heads. I ported the manifold and then used 88/89 Corvette exhaust manifold exhaust gaskets. 40 thousand miles and NO LEAKS