I have removed LOTS of front and rear wind screens without ever cracking the glass. The problem is that the rubber gasket gets hard, and you crack the glass trying to pry it out. The tool mentioned above works great in a lot of instances, but not so much if the glass is held in with a gasket that has turned hard. I am 99.9% sure that a 69 dart rear glass will be held in with a gasket. You will need a razor cutting tool and several blades. Take off any exterior and interior trim. Then you will literally cut away the rubber gasket a piece at a time. Once you get ALL of the outer part of the rubber gasket cut away to the point where you can actually see the lip of the glass all around the edge, try GENTLY pressing out from the inside. Do not try to pry on it. It might come out now. If it comes loose places, and sticks in others, use the razor to loosen those places. You will need to cut away at the rubber from the outside and the inside. If it doesn't budge, cut all around the edge of the glass with the blade resting against the edge of the glass and pointing towards the inside of the car. Then cut away at the inside of the rubber. You will probably go through several blades. Eventually it will come free. I guarantee this will work, and it doesn't really take too long.