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Assuming your Jeep is "stock" you'll need to remove the 4 bolts holding the two straps that secure your drive shaft to the rear differential.
Once removed lower the end of the drive hsaft down and simply slide it out of the tcase.
You'll need to have a catch pan handy as some tcase oil will leak out. Not much, just some.
You'll now need to remove the 4 "C" clips that secure the front u-joint bearing caps and then remove the bearing caps and bad u-joint.