In my 900S (sedan body) it looks like a piece of board similar to what's sold here in Australia as 'masonite', but it's slightly thinner (about 4 mm) and has been vac-formed to sit in the space behind the rear seats. It's got some water damage (though the rear windshield on my car doesn't leak), so I might replace it with something cut from standard-thickness masonite board. The slightly thicker board will also hold the rear speakers better as the thin board just becomes an extension of the speakers at bass frequencies.
8-)
There are a couple of Ebay sellers who marker AC conversion kits but most people don't have any equipment to remove the old fluid, safely store it for disposal, and re-fill the system with the newer fluid to the correct pressures.
I've just recently joined this club and am eagerly awaiting my first copy of Saabmissions in the mail!
I have a couple of spare wiper motors here. Just sitting in my parts collection.
The Bentley manuals are better, but both used together are very good.
I keep a Haynes manual in my 900S and the Bentley manual is here at home since that's where I do all the work on the car.
Craig.