But .... if the groan is coming from the transfer case, does it mean that there definitely IS a problem where it needs to be replaced? I can just hear the Service Manager telling me, "It's not a safety hazard and doesn't affect the performance of the vehicle". But, fourfourto, how does that explain the feeling in the brake pedal that I get (and you, too, I think) as the groan is occuring? Yesterday I had the radio up high and when I came to a stop, I 'felt' it in the brake pedal.
SO, I turned off the radio and brought it to a similar stop a block up. Sure enough, I heard it.