actually sounds about right for that milage, people don't give the trannies enough credit, because these are mustangs and we do run them pretty hard.
good luck with it, sounds like your seeing early belt failure, might be worth letting a tranny guy drive the car, as sometimes they can help you more now than after total failure and it may be nothing at all, I can't give a lot of help because im not an AOD specialist.
let us know
93 mustang notch
~450hp 331 stroker - Sold