I have a 1969 XR-7 Convertible with a 351W (M code) and a factory 4 speed. The passenger side manifold has a casting number of C90E-9430-B and is cracked beyond repair. I found a good deal on the internet on a manifold with a casting number of C80E-8430-B. The guy selling this manifold said it is the same as mine. Does anyone know if these manifolds are the same?