I was in touch with Mercruiser and they ran my serial numbers for my 7.4' s. They told me I have raw water cooling. Here's a photo of my manifold and elbow. I will be replacing both or maybe just a cleanup and bolts and gaskets. These manifolds are actually fresh water cooled correct? They have two lines to them with a separate raw water line to the elbow. Thanks for any info. I'm thinking maybe this was done aftermarket? But the main question is that these manifolds are antifreeze cooled with the block correct?
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