Late model e50 cases. These are the 3 bearing cases with the large transfer surface area. No welding on these needed for the big kits. Swap the guts from your old motor into these. These do have 2 restrictors that need to be removed. One is where the cylinder skirt sits and the other is on the side to prevent installing larger sprockets. Grind them off and epoxy them shut or thread them with a tap and plug them. It is still easier than building up transfer meat.