the hard top has a wiper motor mounted in the fiberglass and not on the window. It also has/had a rear defroster. Every hard top I have seen with a wiper motor has been mounted in the glass and if I try and order a glass for it they ask if it has a wiper and I tell them yes but its not in the glass.
Try searching for the following. I'm not sure what their exact email address is but the shipped me a rear window for my 91 hardtop at about a third of the price of my local glass people. Installed in just a few minutes. Make sure you tell them how many pre-drilled holes you will need for your mounting.
Now if I can just find a good rear window cheap or trade my hard top for one with glass I will be ok. I could also use a soft top if someone is interested in parting with one.
Mine came without a back hatch, I thought no prob I will just buy a new one since the top was so cheap, HA, long story short, I made one of plexiglass. All components available at Lowes. I used aluminum Uchannel mounted to the top between the hinges(use sticky foam strips so your mounting screws dont jingle up the plexi), I made a cardboard template then cut the plexi, and belt sanded to perfect fit. also for the bottom I used the h channel used for those fancy poly decks w/latice(the plexi fits into the top groove and the bottom groove fits nicely over the lip on the tailgate),locking hardware is optional,your preference(I used slide locks). I call it the Fred Sanford Window.
It works, and the whole thing cost me under 75 bucks!