The big rear window is held in with a gasket just like the windshield. I've has mine out twice without disturbing the engine or even the engine covers. The gasket and window can be worked out starting from the top center or one corner; rubber lube might help. And remember, you're not trying to save the broken glass so just push it out toward the engine. Some vendors have glass and Lucite replacements in stock- that window is the easiest to repro 'cause its flat.
PANTERA INTERNATIONAL
A DE TOMASO CAR CLUB
Presents the De Tomaso Forums
The On-Line Meeting Place for De Tomaso Owners and Enthusiasts From Around the World
Clicking on the banner will take you to the sponsor's website.