Front axle noise in 4WD

Has anybody ever had a bent or tweaked front axle housing? My XJ makes a loud noise (sort of like grinding) in 4WD (full or part time). The front ring and pinion and case has been replaced, the front drive shaft has been replaced and the transfer case has been replaced. The shop thinks it could be the axle housing. Any input will be appreciated. Thanks.

well, if the gears, tcase shaft were replaced, i would say its either the tubing, or bearings? someone else?

your front axel shafts are moving at all times 2wd as well as 4wd so if the noise isnt there during 2 wheel drive then id look onto the u joints and if you have a pinon gear problem. could be that it isnt torqued right and with it in 4wd (powere applied) its moving around. Just my 2 cents