[somebourbon]

drill a small hole in the end of the crack to keep it from spreading and weld it up.

I second that. Drilling a hole is crucial. That housing is cast. Make sure you have someone weld it that knows how to weld cast. It requires a different method. This is for cast iron, but I'm sure the same idea goes for aluminum. Good Luck

http://www.lincolnelectric.com/knowledge/articles/content/castironpreheat.asp