buy later model t-stat housings. you can make the old ones work, but they are old and rusted up.

how do you know his are rusted up,have you seen them?

Im not sure what you mean when you say you only need "4" total.

Normally, when upgrading to some performance manifolds, you only need one 1" water hose feeding the exhaust manifold. If you have a t-stat housing that has 2 outlets per manifold, like most factory mercruisers, they make a stainless Y fitting just for that purpose. This way you get water to the manifolds when the stat is closed.

( MILD THUNDER) My center rise manifolds have water fitting on the bottom of the manifold and water fitting on the riser and a small fitting on the riser that goes to the trans cooler (TRS drives), that makes 4 water connections to the exhaust per motor.

I have pics of my stat housing don't know how to put on here. What style stat housing do I need to use?

The old log style manifolds have water inlets/outlets at both ends of the manifolds and 1 on the riser, and a small 1 on the riser for the trans cooler. That makes 3 per manifold, 6 on the stat. 4 bellow the stat, 2 above the stat.

My center rise manifolds are mercruiser