Good question! Have a look at this website:
Red Line Synthetic Oil. 75W85 GL-5 Gear Oil

In the description, it states: "This product is not designed for use in most manual transmissions or transaxles with synchronizers, as extreme slipperiness may cause shifting problems"

On the bottom of the page, under "PRODUCT DETAILS", it states:
"Exceed API GL-5 specifications"

And under "OEM COMPATIBILITY", it states that it's compatible with:
"Toyota/Lexus 08885-02506".
This is referring to:
"Toyota Genuine Differential Gear Oil LT 75W-85 GL-5: Toyota part #: 0888502506"

As far as extra additives for LSD's, it does state:
"Contains additional friction modifiers for suitability with clutch-type limited slip differentials"
The word "additional" in this statement makes me think that it works for LSD's in ADDITION to what it was designed to do.

So, because it lists "Toyota/Lexus 08885-02506" and that it "Exceed API GL-5 specifications", personally, I feel confident using this. However, as stated at the very top of my post, I do mention that I'm not the most mechanically inclined person. I'm just doing the best that I can to do as much of my own maintenance as I can. Taking a 4Runner in to the dealership to JUST do an ATF CHANGE (not flush) I've been reading is between $350-400!!!
Anyway, I'm not guaranteeing anything, but I'm doing everything that I post to my own vehicle, if that gives you any comfort. Taking your 4Runner in for ALL the recommended service intervals..... you would end up spending what the car's worth after a decade! LOL. Screw that!
I hope this answers your question!