I think my head gasket might be leaking between a coolant passage and a cylinder, some others suggested that might be the case on a different thread. It is incredibly inconsistent white smoke. But yesterday it started running around a in normal on the temp gauge. Can you pull the heads off and put in new head gaskets and tighten them down with studs without cracking the heads? How prone to cracking are the 6.9 heads? It is a late 6.9, MY1986