The 84 should be a SJ410. Which, as stated, has an ebrake mounted to the rear of the tcase. While you can swap in a samurai (SJ413) tcase, the tcase gear ratios are not the same between the two. So that will throw your gearing off a little. SJ413 tcases have a 1.409 high ratio and a 2.268 low ratio. I don't recall what a SJ410 tcase has for ratios...but I know they are different.