Engine noise - thoughts?

[fear_nothing]

http://tinypic.com/r/2iub2g2/9

Kindly take a listen to this video. Leaning towards a leaky header gasket. Truck starts, and runs fine. Steady oil pressure etc. Would like some opinions before attempting to remove the rusty header bolts. The noise seems more pronounced from the left size of the engine.

 

[skunked]

sure sounds like an exhaust leak to me. Might want to check the collector first, you should see the obvious black exhaust marks where it's leaking.