You must check your owner's manual (if you have it) or the sticker on the transaxle itself for the correct fluid type and specifications. The sticker is usually located on the transaxle housing.
Failing that, you'll need to determine which transaxle is in your Bronco II (likely a Mazda-sourced unit) and then research the proper fluid for that specific model number. This often requires looking at parts diagrams or contacting a Ford or Mazda specialist.
Trying to guess the fluid could lead to serious transmission damage. Getting the correct information is crucial.