One problem about cracks in metal. If you do not take a drill with an 1/8" bit and drill a coupld of holes at the end of the crack, your repairs are likely to fail. I drill two holes a 1/4" apart, starting at the end of the crack. The reason I do 1/4" is that sometimes you can't see the end. This way if it is past the first one, the second should get it. The JB will do a good job. I know of a friend that purchased from BP some alum sticks that with a good butane torch, he was able to fill in the crack.
Good luck
Chuck
From Steve Wunderele - 10-2-84 --"A fishing trip maybe brief, but it's memories are endless."