I think this may have been the oddest time in Schwinns history.
There was the Waterford Paramount and the PDG OS Paramount (the latter being made in japan with tange tubing)
My bike is a 91 PDG OS3
Mine has the large lettering pARAMOUNT on the down tube with the PDG OS3 on the top tube.
Oversized tubing (as I understand it) was being used as that interm gap between the titanium and CF bikes to come. It supposedly afforded a rigid BB while still giving that great steel ride.
BTW that is a beautifull bike you've got..Not a bad price!