THe 89 and 90 Bronco should have the same model transfer case, the Borg-Warner 13-56. THe only problem would be trying to switch from the electric shift to a manual shift version of that model. (That requires a complete t-case swap with all of the linkage.) Even if the automatic transmission is different from the 89 and 90, the tailhousing bolt pattern for all of the Ford t-cases is the same for 80-96 model trucks/Broncos. There are many posts on this subject if you do a forum search. IF the donor t-case is not a Ford version, you'll likely need an adapter from someone like Advanced Adapters. THey make it possible to mount most any t-case to most any transmission in a 4wd rig. IF you post the model number of the donor t-case you want to swap, that would help, too. There are a few links to t-case ID in the Tech Articles forum. Good Luck, and Welcome to Bronco Zone!!!
JSM84
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