The good thing is that of the glass to replace in your topper, thats the most simple. Look at craigslist, ebay, or a junk yard. You shouldnt have a hard time finding one. Their call the "quarter glass"
They are a bolt in peice. To remove, unbolt all nuts from inside. Then using a panel tool(or wide tipped common screwdriver) placed between the glass and fiberglass topper at each bolt location twist/pry the glass out; slowly loosening and stretching the butyle tape untill the glass can be removed.(start at the bottom front bolt and be sure you pry between the encapsulation and the topper, not on the glass itself) after the bottom and sides are free you will be able to work the glass side to side from outside pulling up and out simutaniously. Clean butyle from the topper
To install, simply get a roll of butyle and place it around the interior surface of the glass, outside of the bolts. Make your seam at the bottom. Line up holes for tge bolts and lightly press the glass into the topper. Tighten bolts starting with the rear top bolt working to the front bottom to assure the glass seat correctly.
You can get butyle at most auto glass shops, parts store, or online at C.R. Lawrance. Its just a black tar like material that comes in a round strip. You can use solid butyle or foam core 1/4" thick. Either works.