Does any one know other than replacing the exhaust manifold what you can do to the hot box valve to stop it from leaking?

Some people dismantle the two manifolds, then remove the flapper valve completely with a gas axe, then place bolts, with washers & nuts in the holes. Seal it with muffler putty, & reinstall.

You lose the benefit of the flapper valve, but if it is leaking badly, you at least get to shut it up.

Make sure that you have new hot box bolts & gasket BEFORE dismantling the two, & undo the old bolts carefully. If necessary, drill the heads off to avoid breaking them off down the threaded hole. Once separated, you can apply heat to the exhaist manifold with the oxy torch in the thread area, & use vyce grips to carefully humor the bolts out of the manifold.

Once the bolts are all out, chase the threads with a bottoming tap, clean everything, & reassemble with new bolts, using some high temp anti sieze as a lubricant on the threads.

Do NOT do these bolts tight untill after the manifolds are fully secured to the head. Just nip them up lightly, then when the manifolds are installed, they are also correctly aligned. NOW you do these bolts up tight

Is it leaking from the shaft of the flapper valve (heat riser)? A machine shop should be able to put bushings in.

Yeah thanks for your ideas. I got some hi temp silastic and gooped it up for a start then i will go buy extractors if that doesn't work.