I have the same boss on my 32. That white disc is indeed for the hicas. I think it essentially needs to be in the same place as it was when you took the wheel off. I had to turn mine a bit to get my boss to line up, which threw my Hicas out of whack. The light would come on after 10 mins of driving, and if I floored it hard from 60 to 70 the back end would start to crab out. Ended up getting the Tomei Hicas locking kit fitted, and the car handled even better than before I messed the Hicas up. Rear end doesn't twitch over rough roads anymore.