Since when did dealers replace 4-Runner driveshafts with Lexus driveshafts "under warranty " . My recollection is that Lexus replaced their driveshafts under warranty but Toyota never did . I gave up on my 2006 Sport , which now has 193,000 miles long ago when after many complaints, I was told it was a "maintenance issue" and regular lubrication was the fix and I was responsible for doing it .
Since when? Well, maybe the dealer where I bought our used 2003 V8 Sport never got the memo to not replace the driveshaft

.
But I was seriously impressed with how they dealt with this situation back then, and am still very happy with the result. And I keep every receipt for everything ever done (not just on the T4R), so I have the dated paperwork for the warranty replacement (no personal cost) and the part number to prove it.
I recall having a discussion with the service manager at the beginning of all this to talk about the clunk. I took him out one awful morning for a test drive in very bad winter conditions. I made sure to do donuts in a vacant parking lot, slam and then feather the brakes, fwd and reverse in high and low, lock and unlock the differential, controlled 4-wheel drifts (without crashing into anything), slow and then very rapid acceleration, etc. etc. -- perfect for demonstrating the clunk, over and over again. He then drove it too, made it clunk repeatedly, absorbed all of that experience, and agreed that work was necessary.
He immediately suggested even before we got back to the dealership that all the universals should be fully inspected, etc., and that the driveshaft might need to be replaced. So, as soon as we got back, the full inspection took place. When they didn't find anything, he orderd the replacement driveshaft, arranged the appointment, did the warranty paperwork in the background, and then a week or so later the full job was done.
I also recall that the difference in part numbers between the Lexus and Toyota driveshafts is only the last digit in the string, one number different. BTW there was no argument whatsoever from Toyota Canada about covering the warranty replacement and labour costs -- it was accepted right away and went straight through.
In our case, I think we were very lucky to have the Lexus driveshaft replacement suggested by the dealership and then carried out so efficiently. And, success of the replacement without any further intervention has been very well demonstrated, now over the past 6 years.
For whatever reason, the dreaded drivetrain clunk seems to be a symptom of some kind of design fault that, to my knowledge, has never been resolved by Toyota. It may have to do with tolerances in matching splines, or something like that. So it could be that the Lexus tolerances are slightly "tighter" than those in the Toyota version. If so, that would snug up any "slop" that might otherwise generate the clunk, but still permit the necessary movement of linked-up moving parts.
If this sounds plausible, maybe such a difference in tolerances would be on account of a difference between wherever either Toyota or Lexus sources parts such as driveshafts -- which country, which plant, which manufacturing line, maybe even which materials, etc.
BTW, I am not an engineer of any kind and don't work in the automotive industry, never have -- I just do one hell of a lot of reading.
Again, I hope recounting this story might help, somehow.
Cheers / Blueleezard :cheers: