1980 470 Mercruiser

[spareparts]

you can replace it, but unles you find a good used dead engine to get the parts off of,its going to be expensive$$$$$$. personally, I'd prefer the cast iron manifold, they gave a lot less trouble. I think your engine has the 3" exchanger, you would have to upgrade to teh 4' if you run the alumium manifold(aluminum transfers more heat)