The crack in the muffler as seen, as seen above was only the outer layer and didn't go any deeper. I purchased some muffler concrete for $2.00 at my local auto parts store. This stuff was gray and thick. I applied it to the crack, mushing it into the crack with my finger till I had it completely covered. Then I let it dry for 24 hours. Once it dried I used fine steel wool to rough it up some since it left a very smooth surface. I did this so the paint would adhere to it better.
Unfortunately I neglected to take close up pictures of the patch before painting it. I have only this picture I took from a high resolution version that is posted below.
