There is a really good post in this forum outlining how to install a new XJS convertible top, but there isn't much on the rear window. I did one a couple of years ago and installed the window before stretching the top on the car, which lead to some problems later. I am about to do another one on a '95 2+2 and I'm being told it would be better to first install the top, then cut the hole in the rear and install the window. Anyone want to weigh in? Thanks

 

That's how trim shops do it.