Exhaust leak. What are the possibilities?

I can hear what I think is an exhaust leak when I drive beside concrete barriers, guard rails, etc. It's kind of a loud ticking sound.

The muffler and the pipe between the turbo and muffler seem to be pretty solid and I don't see any movement. The muffler is kind of rusty at the clamp joint and may even have a crack or small hole that I cannot see. If that is the case, I think it would be an easy fix.

On the other hand, what is the likelihood of a cracked exhaust manifold or manifold gasket being bad? I can't determine exactly where this exhaust noise is coming from.