All I know is what I was told by the previous owner. I have not torn into to see if the prior owner was full of BS or not. I dont have ANY hopping or banging at all. Nothing seems to be binding up to make it even act like that. You are correct, drifting this car would be a breeze. If you even think of blipping the throttle in any kind of a turn, slow or fast the rear end will slide out, the distance it slides out is controlled with your right foot.
You may well be correct and its just a plain posi unit. I will have to pull the cover off and take a look.