I make my own spanner wrenches for those nuts by welding pieces of square key stock to a piece of water pipe, or even exhaust tubing. Drill a hole in the other end of the pipe for a piece of round bar for a T handle. Use the nut as a template, clamp the key stock into the slots with a worm drive radiator hose clamp, and slip the pipe into place before welding or brazing the key stock. It might be necessary to grind the outside diameter of the pipe a little to get a snug slip fit inside the square pieces. You might need to do a little filing or grinding on the tabs to get a good slip fit to the slots in the nut.
Jerry
