I'm ending the project. I'm chickening out. After prepping the the used alum 50? year old housing, on close inspection there seems to be an awful lot of minute casting? cracks. When I started I dismissed them as casting lines, but after grinding away some threaded unneeded bosses, and discovering numerous porosity inclusions, I looked closer at the casting lines, my suspicion, they are from thermal cooling shock when cast, or something, they don't look to be always in use stress related, although some do. Bottom line, not worth trying to make a safe silk purse out of a pigs ear. I'll get the QT bellhousing, save my efforts for something else. Below are a couple of pics on my added lower cover retaining holes. I also under stand there are few if any good methods to locate cracks in alum. Is this a rarity what I am seeing, or common?