Ford Repair: F-350 Exhaust leak, silicon hose, catalitic converter

Question
I have been trying to find what I think is an exhaust leak on my 1992 F-350 5.8L 4x4, with 97,000 miles. Sounds like its up front around the exhaust manifold. I did find that the small metal line that goes to the catalitic converter was rusted through where it goes into the cat. I fixed this with a short piece of silicon hose and now the leak is alot louder. Its just real difficult to isolate this.I was going to take the exhaust manifold off to check the gaskets,but the bolts on the exhaust manifold are rusted and rounded so bad that a socket is useless, and I'm not real sure if its coming from there anyway. Could something else be making me think this leak is coming from the exhaust? Any suggestions on the rusted and rounded bolts? Thanks, Jim  

Answer
Hello and thanks for the question...I'll try to help.
 What I would check for a broken air valve........it's the most likely cause of exhaust noise in the engine compartment. As far as the rounded bolt heads........there is a specialty tool set of sockets. I would ask a MAC or SNAP-ON tool rep for details.
Hope this helps,
Erik