I know this is an old thread, but I recently did my 99 4x4. I unbolted the engine and transmission at the crossmember, raised the engine as far as i could in the engine bay, removed starter, unbolted front axle and let it hang down on the lower control arms, removed the CV axle on the passenger side, then unbolted the oil pan. When you drop the pan, the pickup tube will prevent you from removing the pan completely from the automatic transmission. I took an air cutoff wheel and cut the inspection plate so i could remove the bottom half of the inspection plate without unbolting the entire plate. I was able to remove the oil pan at that point. Clean the oil pan with brake cleaner and a Scotch-Brite(R) pad, new gasket, some gasket maker and I also used the tabs to line up the holes. Re-assemble is the reverse.
Of course, i ruined my two front ball joints and noticed the CV joints were bad so I replaced those and my experience was not nearly as smooth as I just made it out to be, but if I did it again, I think I could do it as smoothly as noted above. I also found out 2 of my 3 bolts that go into the driver's side engine block were snapped off. When looking at it, the threaded part on the engine block that comes out to meet the mount had snapped off. I managed to get new grade 10 bolts in there with locktite and was able to thread about 1/4" of the new bolts into what was left of the threaded area still left in the engine. Perhaps the previous owner was in an accident?

Either way, the truck shifts much smoother now!

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Kawasaki GA