That's really interesting - I'd not even thought about it having a VC, I assumed in my innocence that it just had a normal central diff lock. I'm guessing if the VC is acting up it could be catching unnecessarily or inappropriately, and acting like a locked diff. If it was happening now and again, this would also explain some drive line shunt on the road, I guess. The question is, does a failing VC also start to make nasty noises? Interesting....