Armed with a cheap “10 in 1 Trim Tool” from Amazon and a dozen YouTube videos I started working at the trim around the rear window. On these old Mustangs the chrome trim around both the rear glass and windshield is held in by metal clips that are notoriously difficult to release and the trim itself has the structural integrity of used aluminum foil.
Working very slowly I was able to free the trim on the top and the sides of the rear glass but the bottom strip was just not having it.
By the time I finally broke the bottom trim free it was all but destroyed.
With the trim removed I was able to run a box knife through the gasket around the edge of the window then gently press the window out off the car from the interior. I’m fairly confident that the window and sealant was original to the car, the next photo is a closeup of what I was fighting with.
As opposed to the likely-original rear glass the windshield was replaced roughly 3 years ago by a Mustang shop in the Bay Area due to a rock chip. After popping off the wipers I was surprised to find that the windshield sealant was still highly pliable and though the trim came off much more easily it also made an incredibly sticky mess.
All of the window glass remains in place in the doors, I’ll get around to that before too long.