Bad valve body it would start, but not shift, correct? Unless the ecm is looking for a signal from the tcm that is not there. In which case, I would expect some codes to be thrown. There are also factory and aftermarket valve bodies (called the mechatronic unit) available for these transmissions for roughly $2k, and there is not 2k of labor required to install them. Trans doesn't have to come out. Something doesn't pass the smell test here.