A good welder would probably be able to fix that if you could find one who would do it. He would grind the crack to a "V" so that the opening would be completely filled. He would also know what type of rod to use. My Dad was a welder and I've seen him repair engine blocks and other cast pieces like that, so it can be done.
If it were me that would be the excuse that I would need to swap to a newer front axle with disc brakes. The cost of having that one repaired and putting new pivots in it would go a long way toward the cost of a newer style axle.