when i changed my rear gears, i needed a new speedo gear......the one i bought was for a t-5 but they said it would work with the aod......i think thats when the gear isn't exactly right and can wear quiker..
the aod gear has a i believe a shorter post at the end but maybe it's the other way around i cant recall.....
but yeah do as the above poster mentioned because i think thats where the difference is, they have two different speedo drive gear clusters depending on the year of the tranny.....
and i'll prolly go ahead and get the new one. but its strange, when either of the 2 types are on the speed sensor, the gear teeth will end at the same spot, its really just the nipple thing that is longer like by 1/4inch