If you have access to both transmissions check the identity code on the transmission. Something like PRA-CBA, if the two codes match then you have a winner. If the codes are different then it gets a little tougher. Try googling the codes if they are different, the transmission rebuilders will have listings of vehicles for the various codes. See if the codes come up with the opposite vehicle in anyone's database.
P.S. I am searching for a 5.0 or 3.8 4r70w as well as a e40d for a 7.3L.
