You are going to have to remove the thermostat housing from the block.
so order the gasket for that. two bolts hold it onto the block.
Any hydraulic hose shop should have the hose, take the fitting with you for the size.
Mine leaks also, I have had it off a couple times. then it stops leaking, now we are back to weeping some. My Indy said to put a coating of Permatex gasket sealer on the inside of the hose. that brown goopy stuff, part 2-A. when I get reeeeel motivated again, I dive into this one more time.
Charlie