Well, I feel like an idiot. While watching some youtube videos regarding drivetrain issues I noticed a 4runner had the slip joint of the rear shaft mated to the transfer case whereas mine is at the rear diff. reviewing the repair manual I confirmed mine is indeed on backward. This had to have happened when I attempted to install new u-joints last summer but was unable to do so. I'm going to flip it around tomorrow night and hope it fixes my issue. I just hope I haven't caused any damage to my t-case or rear diff.