Odd...maybe he meant torsen diff?? Can't see why a spider diff would cause a reversal of the 'norms'. I had a spider in mine too. On the other hand, since a torsen has almost the opposite effect to a standard diff, I could see why that might be advised for that type of diff.

I'm not saying he's wrong, maybe he knows something I don't, I'm certainly no guru myself...I would be interested to hear any explanation he could offer for this...maybe we could all learn something, 'cos that setup is downright strange in my experience.