I've narrowed several through the years using my method. I thought about a how to, but decided against it. It involves a plumb bob Kitty made from a 3/8 nut and some red ribbon. Real redneck stuff, but it works and will get it just as accurate and any other method. I've never used the rod and fittings that hold the ends in place. I use the third member and the axles themselves. It's real easy to get it right.