I have an 89 iroc-z with a 350 tpi and auto trans. I am wanting to put on a set of factory exhaust manifolds back on my car, and a dual cat set-up. My car has had headers and a single cat on it since I have owned it and I have decided to put the factory manifolds back on it to make it original again. I would like to know what are the casting numbers on the exhaust manifolds for the dual cat set-up and are the manifolds different for a single cat, or are the manifolds the same for both set-ups. Hope someone can give me some help on this set-up as I basically need the manifold casting numbers only. Seen a few different types of manifolds and I want to get the right ones. Thanks for all who can help.

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1989 iroc-z 350 TPI, auto trans, leather int. t-tops, edelbrock headers and cat back system, SLP cam, crane double roller chain, 4 wheel disc, and aftermarket hood. Iroc-z's forever, Ford Mustangs NEVER