I've got an '02 and it's been a fantastic truck. I haven't had any major problems and it runs like a top with 125,000 miles. I have driven this truck all over the country from coast to coast, it's been in the mountains, on beaches, in the desert, in the swamp. I've moved with it several times, towed all kinds of things, even rescued stranded people with it.
Some of the minor issues I've had are the 4x4 module going kaput, slow leaking A/C system (I charge it every spring), and just in the last month grinding from the front wheel bearings/hubs. I had another spark plug issue which was my fault (wasn't using Platinum plugs). Outside of those things it's just been wear items. I typically use Mobil 1 for everything (engine, transmission, transfer case, front and rear end).
There have been no issues with the transmission, rear end, rear springs, engine or electrical. I am completely satisfied with this truck.