Got a Dodge 600 convert with broke rear glass. (the piece in the convert top)

Owner has 1985 convert Lebarron IF necc for parts. (has good rear glass)

Options?

Is there a "non glass" replacement I should be considering? I've heard of Lexan or eqiv replacement rear windows for other older convertible tops and that they are a better choice because they don't shatter.

Are there still NOS pieces in the community?

What is the difficulty level changing one of these? (never done one before) Looks pretty straight forward, although I'm guessing special adhesive and getting it in straight and tight is prob the whole shebang.