OP, I broke a stock cast bellhouisng like that due to a driveshaft vibration, my fault for driiving the car with a vibration mine was a 1965 Dodge with the old ball and trunion driveshaft, I changed the clutch out and found that someone had put a set of nuts between the driveshaft front U joint and the tailshaft yoke I removed them and tighten it up properly, it(the driveshaft) was to short and tha bound up the front B & T joint making it vibrate Sorry for your carnaged, mine broke the input shaft and bellhousing only I replace the driveshaft and all the broken parts and never had another issue with that car Make sure nothing vibrates in the car in neutral or going down the road