A small 12V cigarette lighter style heater could be added, I suppose. But they draw absurd amounts of power and could potentially burn the car to the ground (seen it happen before) My '74 has the Rear Defroster (Vent & Blower Motor. factory option) and my '72 Demon has the Rear Defogger (in the glass. factory option). I've never even used the Defroster on my Duster, it's not like you can actually see anything through the rear window to begin with Add a bit of a Rake to the way the car sits, and a spoiler, the rear window instantly becomes a "for appearance only" type item The Rear Defogger style Glass is still available, I called a glass place about it after I bought my Demon, thinking it'd be nice to swap my '74 Duster over to the Defogger instead of the original Defroster... Brace yourself... $1,100 for the Rear Glass (tinted) with the Defogger built in :wack: As far as the front defrosters go, if you speed the motor up or try to push more air, chances are it'll make it worse, since the increased speed will just make it blow cooler air. You could always add a Defogger strip to the bottom of the windshield (like on the 1996 and newer Caravans). I believe JC Whitney sells those kits to add the Defogger to the glass.