Check out these nuts. (Problem solved)

Darter6 said

Mopar used brass on the earlier slants exhaust ends before going to that style.
Ever notice allot of slants have at least one of the end studs broken. This is why, many never get installed correctly.
After many years of heat cycles the manifold is designed to allow for expansion,gaskets start to leak thus guys would over tighten.

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Yes, plus they rust all to hell too. But Mopar came out with a service bulletin when that style came out. They were "supposed" to be changed out, because they were having issues with the early manifolds cracking and breaking since they expand and contract at different rates. @slantsixdan has a copy of that bulletin. I tagged him, so maybe he'll post it.