Exhaust Manifold Gasket Leak and click, click noise?

Not a difficult repair. I did just that on my ISL last year. Yes, soaked the manifold bolts with a good penetrating oil for a couple of days before attempting to pull then. Broke zero of them, and that was on a 2003 engine.

Probably good idea to take it to a Cummins dealer for manifold, gaskets and fasteners replacement.

Which way are you headed from Nacogdoches?