Transfer case and rear differential oil change. A kind of easy job, once you do it for the first time. Need a 10mm hex bit to use with a ratchet wrench. Don't go with a simple Allen wrench.... it will be harder. I used the Valvoline brand oil, because allegedly, that's the brand the dealers use. If you decide to buy the oil from a Toyota dealer, it will be more expensive.
Please note that if you decide to do this on your own, you will be doing it at your own risk. Always use caution and take all the necessary precautions. Do your research and make sure you have the proper tools before you make your decision to do your own vehicle maintenance. I'm just showing the way I did it, so don't take this video to hearth.