Thanks for the feedback! It sounds like either the wrong fuel filter was packaged in the correct box or maybe the 05-10 fuel filter was sent to you. Is there a part number on the back of the fuel filter?
The Ford Motorcraft OEM fuel filter for 98-04 Mustangs, is the exact F89Z-9155-A (FG986B) you mentioned working. Which is what you ordered, but didn't receive. I have no problem returning/refunding the fuel filter you received if you want to send me a PM with your First/Last name and shipping address. Or we can exchange that fuel filter for the correct one. It's up to you!
Let me know what you want to do and we'll get this resolved ASAP. Thanks for your patience and feedback!