All original Graham windshields were nickel plated and were found on roadsters and towncars. Replacements are widely available from many sources including eBay. These windshield are bent at an angle to the main, flat portion, a feature that distinguishes them from GM Series windshields.
The part slides into a groove on the body, then one flange is hammered to hold it in place. It is difficult to "un-hammer the flange with the windshield in place. The best method is to remove the body from the frame, then place a screwdriver below the botttom of the windshield and pry up from underneath the car. Unless the body is suffering from zinc rot (many cracks in the body and paint), it will not break.
Once removed, you can attempt to open up the channel for the new windshield. If you try to push the new part down without clearing the way, youl may bend or snap the top portion.