Differential Carrier Capacity (SP|EX long Wheelbase?)

I'm trying to figure out how much oil I need to purchase for my 2020 TRD Offroad DCSB,
AS 75W-85 GL-5 is fairly expensive, I'm trying to figure out how much I need to purchase in advance.

The front diff looks pretty standard at around ~1.50LT, however the rear diff ranges from 3.01-4.28 QTs

How can I determine which Diff and Wheelbase I should refer to for fluid amount?

Should I just assume 6QTS total?

 

After doing some Searching, it looks Like I'm best off buying 6QTs, 1GA + 2QT of Redline 75-85 GL5

 

Ive always gotten around 4.5-4.75 bottles into my rear diff. They are liter bottles so slightly larger than quart. I would definitely plan on having 5 for the rear, but that’s just from my experience. Not sure how much others are getting in. I go until it drips out the fill hole and I let it do that until it stabilizes and stops dripping or drips very slowly.

 

Regardless the amount you buy, people advice ENSURING you can remove the "fill" plug before doing anything with the "empty" plug. No I am not trying to insult but just point out something they apparently have learned the hard way.