My understanding for my 2002 is that the filter kit was discontinued years ago. Filters are available in the after market, yet the hardware mounting kit is not. This had been a dealer add on only. While at junk yards, I checked many expeditions and f150s by looking for the bolts or screws that would be there and found not one. I would have liked to get the 2 frames and cover to mount into mine, but no luck.
Yes this add on required to cut out the bottom of the vent box near passenger firewall, maybe 1 inch by 10 inches, then mount 2 thin, long frames, push the filter in and secure the bottom cover. If having one, then the cover would be noticeable.
I feel that if really wanting one due to harsh environments, then perhaps make a filter for the inlet which in under the passenger side wiper, pull up the plastic grating and inspect.
