'89 - '93 had the AOD, '94/'94 had the 4R70W. To be sure, if you have the O/D off switch on your shifter you have the 4R70W. If you have a TV cable running from the throttle body to the trans, it is an AOD.
Ok, here's something interesting, I rebuilt trannys on my spare time and have done alot of aod, aode, and I've found some trannys that have aode-w on the tag and they use the same hard parts and clutches as the 4r70w, so WTF?