I ran across a 60 f100 today. In the center below dash was a heater box that had three doors on it. the doors opened right and left and the bottom one lifted up. Is this an original box? what were the ***** on the doors made from? the unit had two small holes for screws. The outside of door had a enlongated hour glass shape for the ****. What ***** are these? And is this original?

 

That description does not sound at all like the standard recirculating heater, or the upgrade Fresh Aire heater. It must be aftermarket. I believe that all heaters were optional, i.e. not standard equipment. Can you take some photos?

 

Thanks for your response. I'll get pictures if possible, hopefully by the weekend.