For 2013-2018 g63, I found little info on the diff and TC fluid changes. I thought I’d document it here for anyone looking to DIY

front diff 1.5 qt of 75w140 gl5 gear oil. Any brand such as motul, redline, Lucas, mobil, liquid moly will do
rear diff 2 qt 75w140 same as above

The fill plugs on both diffs are blocked by the sway bar. To get your 14mm hex key and breaker bar in there, jack up the body of the car for more clearance. In the front, I used the mounting point of the sway bar as jacking point. For the rear, the skid plate was used as jacking point. As usual, put some solid jack stands as backup.

‘Transfer case 3qt of 75w90 either gl4 or gl5 will do. I used redline mt90 and some left over liquid moly 75w90 gl5.

the tc was much easier. There is enough room to do the job without jacking up the car. There is a crush washer on the tc drain plug so make sure you use one when putting it back.

my car had 53k mi on original fluid. The old diff oil was thick and dirty. The tc fluid was slightly darker than new but not much wear.

Service interval is 40k mi for diff and 50k mi for tc. I’d recommend doing it earlier than I did, especially for the diff.

many youtube and online sources say the fluids are the same for all 3 thing. That’s not true for g63. On g550 they are the same weight except it’s recommended to use gl4 over gl5 for the tc. I think g500 is the same as g550.

 

GL4 is recommended for the Transfer case due to bronze somewhere in there. (or so I've read)

All your info I found the same - 75w90 for everything, but GL4 for the TC and GL5 for the Diffs. The amounts listed are also correct from my experience.