I'm not defending the mono leaf spring,(I use them on my cars) but I know of a car that had one on it and it broke. Upon inspection of the car I found his cross member at 0 degrees and his axle at 10 degrees, sitting level. If you think about that and what is happening to that one leaf, it could cause it to break and the most logical place I think would be at the locating hole. Just food for thought.