64-65 Barracuda rear defrost set-up

I've seen the rear defroster in the Canadian cars a lot. I tried to salvage one from a wreck but the whole thing was too weathered and rusty. The only time I've ever felt I needed one is when I'm driving the car late in the year, like December and it's threatening to snow out, that's when the back window would fog up. Then the car goes away for the winter and that's the end of that...so I doubt I'll ever bother to get one and install it.