NEW ATLAS CRAFTSMAN LATHE+MILLING MACHINE M644 .
new usa made m644 lock and m645 sleeve for the atlas craftsman 612 inch lathe tailstocks and the atlas milling machine overarm locks and some of the overarm supports. m644 lock has 3/8 square milled pocket for the square head bolt. bolt you have may need to have corners rounded slightly for correct fit in pocket.