I guess a bearing CAN make noise under load only...but He really hasn't checked those bushings yet. From an ease of crossing things off the list perspective...they are VERY easy to check, vs tearing bearings out of the diff or off the pinion shaft. That's the big reason I keep pushing the bushings. Make sure those are good before checking the other stuff. Its two bolts...5 minutes tops, to pop one of the arms out and check it on the bench. So, in less than an hour, he can have all four arms checked and make SURE the bushings are not torn from the middle balls.
He has listened to the noise on jackstands and found its coming from the T-case area. He found a bad bearing in the SYE. Good find, but not it. the noise should still be coming from the same area. So, logically, in my mind, the DC shaft is rubbing because the bushings are letting the pinion angle go wonky. Until he proves me wrong, that's my theory. Like I said, its not about bashing MC arms or bushings. Its just that the evidence, as relayed though the thread, points me that way.