That's exactly the issue. Cannot get a decent enough heat treat once they are cut and resplined. We bought ours new from Moser.
That's what I always assumed it was. It's good to know that the ones direct from Moser will hold up though...I have 33 spline Moser's in mine now, and those should hold for no more than I'm throwing at it lol.
Picked up the new rear end yesterday, put it in last night. Richmond full spool, 31 spline, all new bearings, 456 gears. I get the axels next week. Back to the track soon I hope.