6.9 diesel exuast is making a chattering sound up by the exuast pipe's by the transmission can't find a hole but it sound's like it may be a weld that broke i can see smoke when i floor it but can't tell whear it's coming from it it idle's find but when i floor it it make's this loud chattering sound. it sound like a gas truck with no exuast system thanks

 

Exhaust manifold or gasket? Possibly a donut gasket where the pipe attaches to the manifold. I new to diesels so don't have alot of experience with these trucks.