Dave,
I have an Eaton unit built up with the 31 spline axel. You will never get enough traction to break it. I don't know about the newer soft lockers as no one around here is using them. But Cranky and some of the guys still racing can really tell you what the newer stuff is as they are always looking into it. If your roiad racing is just as a hobby and not serious then you could most likely go with a cheaper trac-loc unit and never have a problem.
Ron
