We have a 1986 Holiday Rambler class C on a Ford E350 chassis with a 460 motor and have spent large bucks trying to fix exhaust leaks between the header and manifold on both sides. I have fixed one side twice and it is now leaking again. My inclination would be to put on aftermarket headers, but my mechanic says that they won't help, and that it is the heat from this motor that does them in. He has repaired it by leaving the gasket off, but it still seems to leak. Does anyone have any remedy or experience in dealing with this problem? Any help would be appreciated.