Yes, you can remove the AW4 from underneath. If you don't have a transmission saddle for your floor jack, consider buying one from Harbor Freight or trying to rent one. If you decide to do it without the saddle use some cheapo ratchet straps to secure it to the floor jack.
Disconnect the battery. Remove the rear DS, drop the front DS at the transfer case. Unplug the harness that runs from the TCU to the transmission. Remove the cooler lines. Remove the transfer case breather tube. Remove the bolts from the torque converter to the flexplate--you will have removed the inspection plate cover. I would remove the CPS/CKP crank sensor and secure it up out of harm's way. Support the transmission with the floor jack and whatever "securing" method you have come up with. Remove the two bolts and two nuts that hold the crossmember to the unibody. Did I mention disconnecting the speed sensors--you need to do that. Lower the transmission slightly to ease getting to all of the bellhousing bolts. Remove the bellhousing bolts. Free up the trans mission and move it backwards. Lower the jack.
Installation is pretty much hooking everything back up. MAKE SURE YOU FULLY SEAT THE TORQUE CONVERTER INTO THE TRANSMISSION BEFORE ATTEMPTING TO INSTALL THE TRANSMISSION--FAILURE TO DO SO WILL DAMAGE THE TORQUE CONVERTER AND THE TRANSMISSION PUMP, AT A MINIMUM. DO NOT TRY AND ATTACH THE TORQUE CONVERTER TO THE FLEX PLATE AND THEN ATTEMPT TO STUFF THE TRANSMISSION BACK IN.
Good luck.
