What kind of oil should i use for the gear box on my 91' Bronco 4x4?

4x4 gear boxWhat kind of oil should i use for the gear box on my 91' Bronco 4x4?
90 weight gear box oil.What kind of oil should i use for the gear box on my 91' Bronco 4x4?
Gear box, power steering fluid. Four wheel drive differential, gear oil.
I believe it is 90 weight. Call the dealer or check your manual.