I run the eaton diff. with superior 31 spline axles. I was going to just buy the ford 31 spline t-lok unit, but at the time I bought mine I found a deal where the eaton was only like $30 more than the ford unit. in all honesty I wish I would have bought the ford unit. Mnay guys have exploded the cases of the eatons, but I haven't seen anyone do it to a ford unit. My dad runs the ford unit in his 11 second '91 and hasn't had an issue and its pretty much a track only car.
I advise against not using the strange SS axles. My dad, my buddy Mike, and I all had them and all bent them. We all switched to superiors and none of us have had a problem since. Mine bent after 4 passes and they bent so bad that the rear rotor was actually making contact with the caliper bracket!