Rear Diff whine again

Just replace your tires with duratrac. You won’t hear that noise. A lot of stories when dealer tried to fix it, noise just become louder. My 2017 has it. Now At 55000 Miles with my second set of duratrac tires, I don’t notice it . No issues

 

Yes! tires with some hum help alot also!! Forgot to add that

 

Hmmmm.... been researching the rear diff whine. no resolutions here as far as I can see. my 21 TRD sport with 6 speed manual started howling at 8000 km, June 2021 took it to the dealer in Ontario and the service guy confirmed my concern on the test drive. Took it to the service bay and the rear diff was making metal. 2 days later they had a replacement from California flown in and installed the carrier assy with great results, no more whining at 100 km/hr. My concern now at 24000 km its doing it again! howling between 55-60 mph. with my research it seems to be more of an issue with the 410 gear sets which are installed in the trd off road and other models with the manual gear box as mine is equipped.Helical cut diff gears should be a quiet as an electric motor if set up properly. As an aircraft Maintenance Engineer for 40 years I do have reasonable knowledge of the workings of a rear diff as compared to a helicopter tail gear box or main gear box.
Truck has been used lightly. I,m told the diff fluid toyota calls up is a synthetic gear oil. I,m looking at scheduling my truck back to the dealer for another replacement but am reluctant until a fix is found. I looked at possibly installing a break in fluid with the gear oil (gear oil with a high zinc content) an aviation product for gear boxes that slows the wear and the zinc allows extra lubrication for the gear set to mate. Probably would not be agreed to by the environment regulators.
I have tried contacting Toyota Canada a couple of times for some answers and just get referred to my local dealer.
I,m not sure Toyota Canada would have any Engineering contacts in Canada anyway. My work habits are driving me nuts, I know I have a failing unit, but the important question is why!
Any help on this topic would be appreciated