I think it's with it, but don't put a low pinion diff in it because high pinion is stronger in the front. Do a lot of research on pirate4x4 before your name a final decision though.
Stock fj80 birfs use the same size cage and bearings as the mini but the bell of the birf is thicker. This makes them a little stronger but not a lot, the chromo fj80 birfs are very strong but I forget if they cut down on steering or not.