Just an FYI, RockAuto shows stock on both the windshield and backlight glazing rubbers, URO brand, and at a very low price. I used the URO windshield one a few years ago and it fit ok.

 

Unless the corners are molded in, better off waiting for an original Jaguar part.

without the corners molded in, its very difficult to get the aftermarket versions to seal in the corners.

I tried 2 of these(there is still one on the car now), same problem.

 

The one that I used in 2018 did not have molded corners, but aside from a small pucker at the very edge, it was fine. Then I replaced the windshield last summer and reused it, and it was fine. I used a CR Laurence bedding compound in the body groove and installed it in the body opening. I then ran another bead in the glass groove and installed the glass; I then ran another additional small bead under the outer lip to the glass and installed the locking strip. Cleaned everything up, then installed the moldings. I also ran another additional bead between the upper molding and the roof and smoothed it into the recess. No leaks either time, and the puckers settled down with time also.

 

I used the URO rear window rubber gasket in 2021. It has been leak proof, but not matter what we tried, me and my helper could not get the bottom chrome on the rubber gasket before I finally decided to just install what we had until I figured out what to do in the future. I believe the URO brand window rubber is just slightly too small. Maybe that has changed.
I'm hoping to reattempt it once I know someone else has successfully installed a gasket that worked out.

 

I reused the OE gasket when I removed the backlight to paint the car, it was still soft and pliable. I also removed the backlight on a junkyard ‘91 and the gasket on it was still good. My advice for anyone attempting is to reuse the OE gasket if it looks ok.
That said, I mistakenly removed the lower molding on mine (thought that there was a lock strip) and had an absolute bitch of a time reinstalling it even in the OE gasket. Ended up doing it in the sun on a 90 degree day.
The order of installation is to put the gasket on the glass, install the upper and lower moldings, then rope the glass into the car, then install the corners.