Small exhaust leak

I have a small exhaust leak on this 318 1974 Scamp coming from where the Y pipe meets up with the passenger side exhaust manifold. I have loosened up the Y pipe and centered the pipe and cranked it down but still a small leak on the inner side between the pipe and the block. Has anyone had this problem, is there a seal or gasket that can be purchased for this problem? As far as I know it just butts up to the manifold and is supposed to seal that way. Drivers side seems fine I have tried 3 times to loosen everything up and make some adjustments but no luck. I do not see any damage to the Y pipe or the manifold and the cone on the manifold seems to fits good into the Y pipe. Wondering if there were different size diameters of the cone from year to year on the passenger side manifold? I think this Y pipe came from a latter year car because it had the bolt up flange to the exhaust pipe or convertor which this 74 Scamp did not have.
Bob

put a fat bead of ultra-copper RTV on it, let it skin and tighten. That stuff is about fireproof that far off the head.