Gear whine after diff fluid change

Yes, I have a 2011 4x4 trd OR with the Elocker and Mech LSD carrier, and a 2009 2wd OR with the same.

 

Nope, when I regeared it, it was the same as my 4x4, keep in mind I bought the truck used so it could be possible it was added.

 

Both of those trucks have the electronic locker and “simulated LSD” that uses the brakes to mimic a mechanical limited slip.

 

Prerunner. My 05 has locking rear differential.

 

Yeah, I don't think we are saying the same thing. A mechanical LSD has clutches that allow a limited amount of slip and sends power to the wheel that has traction. It's actually in the name - Limited Slip Differential. You don't have those clutches if you have a locker. Without the locker on, you have an open diff, but it can simulate the behavior of an LSD electronically by applying brakes to the wheel that is spinning, sending power to the other side. That's electronic LSD, not mechanical LSD.

A mechanical LSD with clutches requires friction modifier. It comes in a tube. It is not already added to gear oil. Gear oil that says it is recommended/suitable for LSD diffs isn't saying it has friction modifier added, just that you can use it in a LSD. But you should add friction modifier.

Friction modifier is not needed on an open diff that has a locker or simulates an LSD by applying the brakes.

 

In 07, the Sport came with the LSD and the OR with the e-locker. The 2WD OR was the PreRunner. There was no brake style LSD AFAIK and it's obvious I don't have it trying to get out of my gravel parking spot.

 

E-Locker and lsd are not one and the same or interchangeable afaik.
LSD is 100% mechanical whereas E-locker is electronically actuated.
Although not 100% accurate the door sticker code should let you know what you have.
You get the axle code off the inside door panel- the last letter in the code tells you whether it is e-locker, open, or LS. A=open, B=e-locker, C=LS
In my case A04C the C means I have a LSD.
I cant imagine how a LSD would behave if swapped in a truck with an open diff with brake actuated traction control but I doubt it would be a good thing.