Hey Guys,
Reading through similar posts, I know other people have had vibration issues as well. However I was unable to find out what the final verdict was regarding a solution to their specific issue. In attempts to get more info. I'd love input from the Toyota Fam here.
To summarize my particular problem, approx. two months ago I swapped out a CV axles because my boot was ripped and squeaking (ie: no grease, metal on metal). In lieu of rebooting I swapped out the axle. After which I noticed the vibration while accelerating in 4WD only. Note, while in 2WD there are no issues, even at hwy speeds. Because I had ordered a remanufactured axle from Rock-Auto, at this point I thought the axle was bad so I ordered a OEM and swapped it out again but the problem persisted. Frustrated with the problem and lost wheeling days, I attempted the following in sequence shown below.

- Swapped OEM CV Axle
- Inspected Axle Seals/Bearing Hub
- Replaced Front Diff Fluid
- Replaced Transfer Case Fluid
- Replaced Rear Diff Fluid
- Transmission Fluid Flush & Replace
- Alignment/ Tire Balance
- Visually Inspected Drave Shafts/ Spider Joint
- Replaced Needle Bearing W/ Clamshell Busing from ECGS

The needle bearing swap for the clamshell bushing last night was my last attempt. Now I'm just pissed and feel defeated. I am taking it in to Toyota tomorrow for a diagnostic. I appreciate any and all input. I will update once a solution is found. Besides being upset, I'm just very curious what problem is.

Do you have a lift on your 4Runner? A lift changes the angle of the CV axle. The changed angle can cause the CV joints to "bind", causing a vibration. There is extensive discussion of this phenomenon on the RAV4 forum. Seems the RAV4 is more sensitive to this.

Sorry to hear about your situation but everything you listed would be the same thing that I would do. Only suggestion that I would have is double checking all your nuts and bolts that you R&R and make sure that your axle is seated properly on your hubs.

UPDATE:

Toyota's diagnostic was bad CV Axle.... They swapped it out, greased the zerker fittings, inspected the drive shafts/ u-joints and the problem still didn't go away. The driver side cv axles is binding when in full droop. After jacking up the LCA it doesn't bind, but clearly when the axle is loaded in 4wd is binds which is confusing. They said my lift was too high which I laughed at as it's only 3". I have a diff drops spacer and there wasn't a problem before I swapped the CV axle that came with the rig 2 months ago. At the time I have a 3.5" lift. When i replaced the axle I took a shim out that was above the strut assembly because that may have contributed to the boot ripping in the first place. I have read many other postings with similar issues. I have reason to believe that the CV binding has to do with my current suspension setup and a zero point calibration. I still have the 2.5 Series Fox Shocks that comes standard with the 2019 TRD Pro's. Since I replaced the strut coils with longer Eibachs and added the shims above the assembly, the preload and extension may have exceeded the shocks capacity. My rig off-roads fine but is pretty stiff, which is why I am doing a full suspension swap once everything is delivered in another 6 weeks or so. I may just have to wait and see how it goes but I am taking it to my 4x4 shop Stellar Built to diagnose as well.

As others have stated I would check the angles and geometry of everything that might have changed after a lift

Had this happen on my Honda Accord: vibration on acceleration typically showing up on acceleration above 45 to 50 mph, like when getting on a freeway. Took it to an alignment shop and they said alignment was fine, but I needed to replace both CV axles. Installed new aftermarket CV axles at $78 each vs OEM at $573 each. Worked great and still running fine 50K miles later.

If not for the lift, I’d say change both. I have no experience with lifted vehicles.

you lifted the runner and the front diff axles/bearings change more wear...
I lifted my runner 1 inch and those front axles a very straight...
I grease my drive shafts every year ...

My rig has been lifted for over a year and a half and binding never occurred before. The binding only started when I swapped out to new OEM CV's. A 3" lift shouldn't cause binding, my axle angles aren't crazy at all...