Advice from anyone on gear oil for transfer case

Is this a GL-4?

 

S.A.E. gear oils are graded on a different scale than engine oil. A 75W gear oil is like a 10W to 20W engine oil. Synchromax's cSt at 100 degrees C is 7.5 so it's right around a 75W to 80W on the gear oil scale.

 

I don't think they can call it GL-4 due to their proprietary additive package. They do recommend it as a replacement for Toyota LF. It's probably fine to use, and in my opinion probably a better choice than a GL-5 gear oil. I just have issues with people telling me it's better just because they say so.

 

Anyone know if they changed the transfer case hardware between the 2nd and 3rd gens? I've got a 2nd gen truck which I want to last forever. (It's a camper and very modified, and would be a nightmare to start over on a new vehicle). The TC's look the same between the g2 and g3 trucks. I'm basically wondering if something actually changed, or if they decided this new fluid was better in the same TC. I see people being concerned about gl4 vs gl5 and the brass parts. If the expensive LF fluid would be better in the long term I'll use it. But if something actually physically changed, I guess I can use the standard gl5 gear oil in the g2 TC, like my owners manual says.