i talked with the owner of erikkson industries who specialize in the 5hp24 and is a great wealth of knowledge and assistance. He thinks that the splined output shaft is the same on all bmw x5 5hp24. Which means as long as whatever tcase you use has the coupling sleeve then your g2g. I talked with another specialist from tcbmwx5.com (good resource) and he said my idea of actuating the motor in the atc tcase would not work as there is more involved then a simple on off function. So the nv case should bolt right in.
However
The whole reason to use a new tcase was to simply have the front drive output flange be new and matched to a new extended length driveshaft for best durability. My front flange is typically worn in the lwx tcase though still engages the also worn front shaft tightly and with no play in the radial/rotating back and forth direction. I ordered a 65$ shaft extension on ebay advertised to fit only the nv tcase but was pretty sure it would work with the lwx front flange. It works but the fit around the splines radially has play/is loose and would surely make a clunk. So i talk to tcbmwx5 and he says that the aftermarket extended drive shafts are loose like that. so theres really no point in going with a new case and shaft. My original tcase other then the worn front flange and stretched chain (which i finally found) is fine. My only other idea to actualy fix the front drive spline issue without creating another problem is to see if a higher quality shaft extension from germany / austria has a spline interface closer to oe.