It makes no sense to me that an axle can make noise when it's not turning. Does the Gen II have disconnecting hubs? On the wife's Rodeo, the front has drive flanges which make the CVs constantly engaged turning the front diff and axles all the time. The t-case is the single disconnect point. Do the later Monties work the same way? That is the only way I can think that the front CVs would be affected in 2wd.

As far as driving around in 4 HI all the time, I don't understand why you'd do that. If you ARE driving that way, then there are a few things in the front driveline that could be making noise and the driveshafts are one of them.

Once again, go get a look...