No actual exp but if I was faced with that I would drain the pan to get the fluid away from the crack then drill a small dimple partway in on each end to stop the crack from spreading then more dimples in the length of the crack between the ends then clean it thoroughly with brake kleen then fill it with JB weld. (maybe drill all the way thru) I am just strickly thinking out loud & someone may have a better solution but here is a BTT for ya & I would call a welding shop & pick their brains & there are some experienced welders on here also