Try this: https://www.trovestar.com/generic/blog.php?Article=421 The author defines some of what your looking for. That really is not enough by itself. What is the impact of a .010 axle length difference? Some of that is dependent on the trucks, the average length from bearing cone to bearing cone & the tolerance in the manufacturing process. As indicated in an earlier post, I am looking into this problem. Will try to answer some questions along the way.