You haven't given much of a description but, if it was sort of a basket type with twin bars about 4 inches apart going around the perimeter, I have seen that type and while I don't know if it was a factory option, it was available through the dealership.

If you go to the EPC and look at any 123 vehicle, then go to section 84 Trunks and Cases, there are a couple sub groups under that, the first one being Roof Rack shows the basket type I've seen. If you look around at the other sub groups under that section there was a whole array of specific carriers, for skis, bicycles, surf boards, for a boat, and there where a couple of different boxes, one long and one set of two that filled the rack for the TDs.