. . . . down the defroster duct (on the driver's side) today when taking the dash pad off. How the heck can I get the screw out? Is it possible to get it through the floor ducts?

 

Hey, another box body owner!

I would try taping a magnet on a piece of wire, or on a length of weedwacker cutting string, and go fishing down the defrost duct. It may have not fallen way down. I don't know if it could make it on its own all the way down. On a box body, it would end up in the main plenum, and maybe jam the blend door.

And, dont ya lose 10 points by dropping the screw down the duct? I know I'm always thinking of that when installing or removing a dash pad..... "watch it! watch it! Carefuuuullll !"