Glass stores should be able to special order replacement glass in the original style. In Kalamazoo, MI, a piece that was identical to the original textured glass was running just under $80.
New door window gaskets may be ordered from Restoration Specialities, part # AS1475. It is a tad larger than the original, but works and is much more pliable than the original gasket.
Many thanks to Don who, September 2010, volunteered to be video taped installing a Scotty door window. There are 4 volumes to this video as replacing the door window is a very time consuming process - unless you do this professionally. Be sure to watch volume 4.
Tips for installing the window yourself
From n4zou: Use mason string and plenty of Armor All. Start by cleaning all surfaces very well. You do not want to have any oil or dirt on anything the rubber seal will be in contact with, as this could cause a leak. Next thing to do is apply the Armor All to the rubber seal. This will lubricate it and allow you to smoothly pull the glass and rubber into place with the string around the door window opening. Place the rubber seal around the glass and if there is a joint make sure the joint is centered between the corners and on the bottom. Place the glass and rubber into the window opening starting at the bottom. Run the mason string around the outside groove of the rubber seal. As you pull the string the rubber seal and glass will be pulled into the window opening. Apply Armor All as required to keep it lubricated, you can't use too much of it! It should pull into the door opening easily and the Armor All will allow the rubber to shift around and seal tightly.
Dominic said: I also used the gasket listed above (WS-AS893) on my 1968 Gaucho with 1/8" frosted plexiglass and it worked GREAT. I recommend the listed gasket highly. The door has two metal panels that are actually held together by the window gasket - you definitely need to use the gasket.
I put the gasket in place first with the seam on top. I started on top and was careful to make sure both metal edges on the door were inside the gasket. I then placed the window in the bottom ridge and started to work up along the sides working it into the gasket all the way around. THEN came the very tedious and difficult task of closing the locking ridge on the gasket. I started in the center on the bottom and worked my way up the right side to the top and then did the left side. I used warm soapy water to make the gasket pliable and eventually had to use a little Armor All on the last (Upper Left) corner. It is a slow go, so be patient. When I finished I could have used a martini. I had a blunt plastic tool that glass shops use to help push the locking strip in as I went along, but a LARGE blunt slotted screwdriver would do the same thing. Just be sure it is blunt so as not to puncture the gasket. Lots of warm soapy water or Armor All to keep the gasket pliable and patience should do the trick. Good luck, it looks great when done.
Dominic added: The trick is time and patience I am afraid. You have to soap it up and use the glass installers tool I mentioned or a very wide and blunt screw driver (so as not to puncture the gasket). You need to start on the right top and work your way around, inch by agonizing inch-holding what you just did in place with your other hand. It is tedious and it hurts. Good luck! Check with any local glass shop for an old plastic pry stick. I don't know what they call them. They look like a carpenters flat pencil.
Nancy says Watch the Videos and then go to a glass supplier and have them do it!