Air Force one filter- need replace asap
#1
#2
I don't think that you can. If you do manage to locate an original, you're probably going to find out that it is deteriorated too much to use. You didn't post a picture so I don't know what the part looks like but you might be able to cast a replacement or have one machined out of plastic or rubber. But it's probably going to be easier and cheaper just to replace the entire thing with a different unit.
#3