[Licensed to kill]

When I got my car about month ago, it was leaking there as well. Upon inspection, I found that the tailpipe clamp was positioned on TOP of the lower frame rail and this put the angle of the flange off so it didn't meet the manifold square. I moved the clamp to the bottom of the lower frame rail and the flange mated perfectly with the manifold, no more leak there. I had a broken intake manifold and the #4 exhaust port wouldn't seal to the block so I purchased a set of manifolds from "Bert's". When installing the new manifolds I found that the flange on the pipe no longer mated to the manifold correctly. I moved the tail pipe clamp back to being on top of the lower frame rail and it mated up perfectly. How I actually did it was to undo the tail pile clamp completely and have my wife hold the muffler/pipe assembly up and had her hold it in a position where the manifold to pipe clamp went on without resistance to ensure a perfect seal, than after tightening that clamp, then went back and positioned the tail pipe clamp to hold up the pipe. Perfect seal.