Yes this is just for the D44. As far as I know the stock Nissan diff is fine as in the past. Both units will need an ARB though, for real wheeling, as the True Trac is just a limited slip, temporary solution.
As far as class action...maybe. That is kind of a wait and see. The denials are starting to pile up, though more on the Titan side. I have seen maybe 2 dozen denials so far between all 3 models. My attorney is also not a class action guy, so he would have to refer me most likely.
Oh, that brings up another thing, while talking about Titan. The Nissan rep jumped up and down practically telling us the Titan diff was NOT the same, because they knew we would bring up the endless Titan failures. Even armed with part numbers and such. Its things like flat out lies, making things up, ect that make me want to pursue this non-sense further.