I've got contacted by a guy, who wanted a NV125 TC in his facelifted X5, because he had troubles with x-drive actuator, so another field of such a conversion would be a NV125 swap, bacause the housing of the GS5 (5 speed on pre-facelift) bolts directly on 6-speed RWD-only Getrag and the housings of GS6 on facelifted manual X5s are the same as on GS5 on pre-facelifted X5 with 5-speed manuals (it's logical due to the same engines).

A S62 (M5 E39 engine) swap in to any X5 (no matter facelift or pre-facelift) incl. gearbox is quite easy too, due the S62 has the same engine mountings as M62 and it's not difficult in terms of electronics.