Ebay, junkyard, ford parts network, dealership. I bet a dealer would have it.
You also don't need it, not having it will not cause any issues. Even California
emissions guys are not going to pull your stock CAI apart to inspect it.
2000 Mustang GT Steeda #0048 34k miles. 99 Cobra 4V swapped, FTBR IRS swapped, exhaust, tuned by James Gordon.
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.