03 e350 superduty van
 

i just replaced front wheel bearings. Did the race and bearings with seals.
im hearing noise when turning. sounds like a 4 wheel drive drive when in 4 wheel. not sure the issue. i have the axel preload many times and nothing seems to help. i used the the manual on preload. 30ft lbs then back off 2 turns. this is all while spinning the wheel. 24 ft lbs then half a turn back. 17ft lbs then back off. then 17in lbs. even rotated the wheel. need help. someone mentioned that it could be the rear end. meaning the differential is going out.