If you have not done so, change the transmission filter and fluid; I would also flush the transmission.
i have a 1996 ford ranger 2.3 4 cylinder automatic ,just had the trans rebuild and driveshaft but theres still a bit of play comming from the differential ea. time i either put it in gear i feel a boom from the rear (not the driveshaft nor trans) is it a big job to replace the rear diff? and $$$ ???? Ron