One problem related to differential unit has been reported for the 2004 Toyota 4Runner. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2004 Toyota 4Runner based on all problems reported for the 2004 4Runner.
While driving vibration came from the drivetrain/front differential at various speeds. Seemed to be related to rpm and outside temperature. Most prominent at @2000 rpms, and below 50 degrees. Vibration felt in pedals, floor and steering. Heard throughout the vehicle. Dealer tech trying, but no answers.