I'm guessing I need 1 inch rubber hose for the hoses that go from the thermostat to the exhaust manifolds? Is this correct? If so where can I buy it? I don't need the pre-bent stuff. Also I have Gil exhaust and I believe they have an 1 inch npt female fitting at the end of the log. When I look on the web sites for different marine suppliers I only see a 1" npt x 1 1/4" outlet for a 45 degree fitting. Is this going to work for a 1 inch hose? I need the 45 degree fitting to get around my water/fuel separator. This is a project boat and I don't have the original parts. The motor used to have a crossover setup, but I'm going back to original thermostat, circ pump setup. The thermostat housing is a stock 4 outlet housing found on the later mag motors.

They are 3/4 NPT fittings. You can get 1" rubber heater hose at most auto parts stores.

Thanks Griff, I measured the barbed fitting that screws into the female fitting at the end of the log, the the NPT side measured 1 inch in diameter. Are you sure they are 3/4 NPT?