I have a Cal 28-2 powered by a Westerbeke W13A. Both exhaust manifold adapters that go between the head and the manifold were cracked and broken causing the exhaust manifold to leak. Westerbeke apparently no longer makes this part. The original numbers were changed to a new number and that number is listed by Westerbeke as No Longer Available (NLA). I don't know how I am supposed to bolt my exhaust manifold to the head. Anyone have experience with this or have any ideas?