Possible Common 4wd axle disconnect issue but with a TWIST!
 

Took a long road trip hunting in my 1996 4wd blazer. Started to hear some grinding noise it what sounded like front right wheel. Got it home decided to do some checking into the noise. For starters the blazer has new wheel bearings front and back.

I proceeded to pull the front right axle out and checked the disconnect. The gear was worn like it had been engaged but not terribly mangled. I had a spare parts vehicle so I went through the trouble and swapped the gear and washer with a better looking one from the donor. Reassembled everything and it’s still there. I unhooked the the cable all together from the front diff to make sure it wasn’t a stuck cable or vacuum switch. Still had the noise. Now here is the weird. If you manually engage the front axle and leave it engaged while driving in 2wd there is no noise. Also if you disengage the front to bring back the noise it will also go away going down the road if you push the 4wh hi button and engage the transfer case, even though the cable is completely disconnected!!!??? All fluids have been checked and or topped off. D