[Synchro909]

I've just sorted a rattle in the windscreen of my '28 Tudor too. It was the screw at the front end of the arm that holds the window open. Once tightened, no rattle.
If your problem is indeed the glass loose in the frame, try a little black silicone around the edges I'd apply it so that some goes in between the glass and the frame, then clean it up Silicone can be removed with Mineral Turpentine easily before it cures.