Yes, the CAF assembly was an option, but evidently very much unused or unordered. Whatever, because it's not available now and hasn't been for most of a decade, I figure. So, F150canuck, you won't see the jazz depicted in the photos, but what all that jazz attaches to.
The ducting is located behind the plastic cover located under the glove box. You can actually feel the area without taking the cover off. But, you will need to get comfy with being in a funny position to get leverage to do this. I was done in about an hour...ish, but that included checking the hockey game score and some gloating once it was done.
You can google F150 cabin air filter install and a couple of Youtubes come up. Watch 'em both. Since this current truck is going to be "retired" to chemical plant/refinery duty once I am done shopping for an '08, this definitely will come in handy for those dusty dirt roads.
One week in and mine is still in place with no worries. I dig these nifty little mods!