Re: salt water question
My boat sits on a salt water mooring 6 months out of the year, and it's been used in salt water at least half of its life, and I replaced the manifolds once and the thermo housing once, and the themostats themselves about every other year. If you are flushing it after use I would not worry. The corrosion issue with salt water is a real issue but it takes years for it to reach a point where you will have trouble because of salt water use. A 1990 Cobra 4.3 will have the one piece manifolds, that are no longer available, I suggest you check em after 5 years of salt water use. If they are getting really corroded, then you can replace them with an aftermarket kit that converts it to a conventional two piece design, but my experience has been that the one piece units last long even in salt. I fill my engine and manifolds with the best -100 antifreeze when winterizing and that seems to keep the inside of the engine from rusting much. I looked in the intake manifold and the water passages in the block when I replaced the water pump and thermo last year and there is no flaking rust in either place.
Oh and salt water is not all bad, keep in mind freshwater rots wood (transoms, decks etc) but the fungus that rots wood can't live well in salt water so you don't see as many rotted transoms on salt water boats....
