Dude....I had a filter in there?!?

Not sure if mine is original or not at 136K.

 

Looks like the replacement one I got. I noticed the factory filters seem to have some extra support in them.

 

I snagged a K&N filter on Amazon. For $35 and I can wash it, seemed reasonable.

 

Many of the older Ford pickups had problems with leaves and fir/pine needles getting stuck to the fan speed resistors which are inside the ducting that would occasionally catch fire, I think I read that on a service letter one time and I remember seeing where the resistors were in my Ford trucks, just above the transmission hump behind the dash. The outside air intake didn't even have a screen to stop junk from getting into the air system, just slots in front of the windshield.