Original windows are "school bus glass". Regular glass (not tempered) with plastic sheet in-between. Difficult to drill the hole for the pull so close to the edge. Acrylic (best choice) or Lexan polycarbonate is easy/cheap way to go. Use black silicone or maybe black 5200.
Tempering results in a harder glass. It has to be done in an expensive machine that only large glass manufacturing plants can afford. Smaller shops have to send it out. Problem is most shops don't want to be bothered with small jobs.
I patterned mine and sent them out to Peninsula Glass in Vancouver, WA for tempered glass. There was a minimum and a little pricey but it is the best choice. Only a little more to have 3 made - $46.60 each - have one left. This was in 2009.
Peninsula Glass Company is your premier custom glass manufcaturer. We pride ourselves on providing high-quality craftsmanship and service. Call us today!
peninsulaglass.com