have you tried your local NAPA dealer? They seem to carry an awful lot of stuff that the other boys don't. Also, try NPD and Mustangs Unlimited - they usually have quite a few things that most other mustang vendors don't carry...
I ordered one a couple of years ago from one of the major mustang vendors. Sorry I can't remember which one. Look closely at your old one and check if it has a 90 degree on it or if it is straight through. Do not let them send you the wrong one!
It would be a shame to have passed the test but to have missed the lesson.