I Googled "toyota clamshell bushing eliminates vibration" to find the following information. The reported symptoms vary … here are 3 instances …
Intermittent vibration/humming while driving. Comes and goes, often more present with cooler temp outside, especially when truck is cold. Goes away when 4wd is engaged, comes back when disengaged.
Vibrations can be felt coming through the steering wheel and seat/ console... they come in consistent wave like patterns every 5-10 seconds, more noticeably around 60-70 mph. feels like motor shuttering slightly but annoyingly because it comes and goes.
Toyota took a look under extended warranty. Removed the driveline entirely and still vibes existed. Installed carrier bearing spacer anyways. Maybe helped a little didn't really notice though the tech said he did. Finally saw this thread and tried 4wd on a flat straight road, vibes didn't seem to go away in 4wd. Checked in the garage any play from the carrier to the CV in 2wd vs 4wd and it was a worlds difference between passenger and driver in 2wd. With the former being stiff from the carrier and the driver side having about an inch of play. 4wd play was gone on the driver side.
Front Diff Vibes ECGS bushing fix. | Tacoma World
Needle Bearing Failure With Lift (How Many) | Tacoma World
Vibrations after lift kit. (Solved) | Toyota 4Runner Forum [4Runners.com]
Levi writes, "It's a problem with Toyota 4 runners, fj cruiser and the Tacoma … extremely common". However, my search turned up mostly Tacoma hits.