I've been working on getting my '83 300SD back to fighting fit and I'm beginning to move on to cosmetic issues now. One thing that has been driving me nuts is a hole in the headliner, not a cigarette burn, but one that was made into it. It's about an inch square and has has molded, rounded edges. It's about an inch above or aft of the domelight. My SD has a sunroof, but the switch for that is in the cluster above the climate controls. Can anyone tell me what this hole is for?