You should post up a little bit about the situation that occured when it broke. Was it just brute torque that broke it? Or was it some wheel hop that was happening? Did your LSD not transfer power evenly to both wheels, or did it do it just too late since it is a VLSD? Any info you have to help others out would be great.
I have had it at the track over the years quite a bit and never had a known problem with these output shafts. (I never pulled them out to examine them either) Last week the local track re-opened after being closed for a couple of years. They re-paved the track, and had a few test and tunes to get some rubber on the track. The day I went, they poured several layers of VHT and the track was like glue. I have a brand new set of slicks and the guy I lined up against had previous times that were almost identical to my previous times. The burnout was great, no issues. My launch was a WOT, 6000 RPM launch and the car went maybe 1/2" on the launch. I let the clutch out, OK maybe I side stepped it, and all I heard was BAM. That was it. No more excitement. It is the VLSD and it has been fine.
I imagine it was major torque, new slicks, glue track and a "little agressive" launch. I wish I could add more to the learning curve.