3rd Gen looking for recommendation on changing diff and xfer

Hello fellow Tacho enthusiasts. Note this is my 1st Tacho and love it!
Year: 2017
Model: TRD Sport, stock (which I hope to mod a little here and there)
Milage: 35k
Driving conditions: typical NE US - mostly highway, light traffic - no off-road at the moment

Between two reputable sources I have been told to either change or not change at or around 30k. My feeling is better to be safer than the alternative.

Thanks for your answers in advance!

 

For diff's I swapped to Lucas 85w140, change once a year. Transfer case haven't touched yet(I should though), it will also be once a year.

 

Follow the recommended maintenance intervals provided by Toyota.