It's not a factory item. Most likely it was made by a company called Saratoga.That company made those hatches for various different cars, like Porsche 944, E30 BMW etc. I suppose you can locate letters "LOF" in some part of the glass. LOF means Libby,Owns & Ford.LOF supplied all glass for Saratoga which build only aluminium parts inhouse. LOF was a major glass supplier for GM starting from early 1950's. Iirc LOF is now part of Pilkington glass company.