Maintenance questions

Can anyone help me out with my planned maintenance for my new to me Tundra? 2017 Crewmax SR5 5.7 4WD 100k miles. I plan to:

Change the coolant,

Change pcv valve

Replace serpentine belt (anyone know the part #?)

For changing the front and rear diff fluid: if I bought OEM fluid, the price only comes out $20 cheaper than what the dealer would charge me to do it. I see alot of people recommending Redline 75W-85 GL-5 and alot of people saying they use Mobil 1

$39 75W-90 GL-5 Limited Slip, Ultra Long Drain 500k Miles, Manual Transmission, Gear/Differential Lubricant (1 Gallon)

75W-90, any input on which direction to go here would be helpful. Also from my research, I gather I need 1 steel crush gasket part #

$14 12157-10010 Toyota Oil Drain Plug Crushable Steel Gaskets Set of 10 OEM 12157-10010

12157-10010 for the front fill plug and one copper flat gasket # 90430-24003 for the front drain plug, along with two of the above steel crush washers for the rear diff drain and fill, can anyone confirm those part #s are correct?

As far as limited-slip additives, how do I know if I need them?

Transfer case fluid, again with the price of OEM fluid, it comes out $8 cheaper than what the dealer charges so ill probably let them do that.

I'm not too mechanically inclined, so I'd let the dealer do the plugs at 120k.
If i'm missing anything or if anyone has any tips on the coolant change it would be much appreciated.

 

Part numbers and fluids for the diffs/TC:

 

I would change plugs and all filters and fluids and also clean throttle body real good and the maf sensor.