Water issues/exhaust manifolds
 

I have a 1996 z252 with a 7.4L. Does anyone know if the original manufacturers specifications for the exhaust manifold? Does it come with risers? The engine I have has been rebuilt and am having to do it again due to water in engine. Not sure where it is coming from. It is well maintained and winterized properly with no cracks in the block. The manifolds are not cracked exteriorly or interiorly. My engine does not have risers on it currently and maybe they forgot to put on, not sure, please help.