This months issue of Hot Rod (April 2017) has an article helping a guy with the same problem your having,only his was worse. Hot Rod Rescue is the article. He went through everything, even taking it to a 4x4 shop because he was being told his angles were off. It was a combination of a lot of things, including transmission dowel pins out of alignment. Right now your just speculating and throwing money at a problem hoping to find a cure. Pick it up and read, very enlightening.