The Transmission fluid is designed specifically for transmission use and only comes in SAE 90 gear weight (14.5 cSt) or 40 weight engine oil, whereas the Gear Lube is a general all purpose gear lube and comes in 80W90 and 85W140 weights.
Specs say the 80W90 fluids have the same viscosity at 100C.
Do you have an apllication for this fluid?