2010 Liberty rear end I had the stock open differential pulled out and a Eaton Detroit Truetrac Differential put in which is a Chrysler 8.25 but in like 08 they started ( using aluminum for the bearing caps in the differential ????

) ok the jeep is a daily driver by the wife, it's all stock everything right down to the tire size and gears 3.73
17 months after having this done the driver side bearing cap snapped in two right inline with the lock bolt, have only pulled a light load with this around 3000 lbs. it has a 5000 lbs. pull capacity. the shop that did the work can't figure why it did it has anyone changed the differential to a LSD and never had anything like this happen? I read guys are going to bigger tires and they say they are going to or did put the truetrac in front and rear. need help with this Thanks for reading.