The best thing to do would be get the car up on a hoist or up on stands and check the uni's etc.
Put the handbrake on and in neutral, see how much play is in the crown wheel and pinion, by turning the tailshaft. If there is a fair bit of play, you take it to a diff shop and get it shimmed up.
Personally, I wouldnt worry about it, unless its really pi$$ing you off.
Mine diff clunks and winds etc, but i really cant be stuffed with getting it done a 4th time, so it will stay.
One other thing ive noticed with EL's and AU's, when you are slowing down, coming to a stop, when the ecu drops the auto back into 1st, you generally get a bit of a clunk.
Funny enough, in two cars i've seen increasing the line pressure (trans module) makes it clunk less, although you would think it would make it slightly worse
, but the next problem becomes a bit more noticable with increased line pressure:
When you are at highway speeds and back off, and you say you feel the drive line unload, its probably due to the ecu not releasing the torque converter lockup at exactly the right time, it might be letting go a little bit too late, so you are feeling it when it unlocks.
There is not a great deal you can do about that, unless the problem is being amplified through the drivetrain due to dodgey uni's or play in the diff.
You should also see the same thing at around 60km/h manually holding in 3rd, when you accelerate very slightly, you will feel the torque converter lock up, and rpm's dont increase dramatically, this is more noticable when going up a slight incline.
If you then back off, you will feel it unlock, which sort of pulls the car back for 1/2 sec or so, then frees up again.
Its pretty normal, due to the "computer torque control"