I believe I found my leak. Check this out:
[IMG]
http://i7.photobucket.com/albums/y261/bohon/56%20Chevy%20truck/ExhaustLeak001.jpg[/IMG]
It looks like I never had it squared up to the block to begin with. I have to think that was because I had the two manifolds bolted together and was trying to fasten them to the block as one assembly. I put a straight edge along the mating surfaces of the exhaust manifold and it is not warped. I still want to replace the bushings for the heat riser shaft but just saw that the flapper is welded to the shaft like Huck says.
