Its a '91 Sahara 4.0L and the 4-Wheel Drive seems to work great (we've had some snow lately here in ND and I've been fine in anything up to the headlights). It shifts in and out of 4x4 fine. However it gets pretty loud if I start going fast (like around 40) in 4x4 and only when I'm on the accelerator. It seems to be coming from the right front. No pulling or steering issues. Also, it is makes some noise when I push on the brake. All of this goes away when I shift out of 4x4, and seems to be coming from the front, passenger side. Anyone have any ideas what's going on?