has anyone else had this problem?

my svx makes a rumbling noise and shakes/vibrates when i make turns at slow speeds, and sometimes when i accelerate from stopping., sometimes it rumbles a lot and sometimes only a little. other than that it drives like a dream. my mechanics say it's either the rear differentials or the transfer clutches in the transmission(probably both) or the trans. all together.

has anyone else had this problem? if so could you please share what it was and what you did about that.....thank you