Well i have herd the second holes are for an exhaust bracket, but they look usable for cross member to me. The 5 speed i sold conehead had the 2 mount points and some 56 a 4 speeds i have seen since have the 2 mount points. As far as specific models they came in I'm not sure others would know a whole lot more than i on this and many other matters or Wiki will give answers ive been using the wiki lately its awesome.