1965-66 Plexi Glass R-Model Fastback Rear Window. Has the original Shelby 1" opening at the top to allow air out of the cabin. Plexi Glass fastback rear windows will save nearly 30 lbs of weight. It’s no secret. Track cars flex during cornering and acceleration. Because of this, glass windshields are prone to crack. Eliminate this problem with one of our new light weight windshields! Our Plexi Glass windshields weigh a lot less than the stock glass windshield and are formed as the originals to fit into the stock rubber gasket. Designed for use on track cars only. Not advised for street use. $15.00 box fee applies. Shipped truck freight only.