A guy I know has a set of 28 spline mosler axles that he says will fit my car. There new and still in box, he wants $125 for them. He said he bought them and then decided to go with 31 spline. What is the advantage if any, of 31 spline over 28? As far as I know my car still has factory axles, would this be a good upgrade for the price? I'm about to have a traction lok rebuild kit put in the car so I figure if I'm going to upgrade then now would be the time. Opinions and info please.