Well, the 203 in my Jimmy is leaking fluid from several areas and I'm thinking about tearing it down and going through it. Will I need any special tools or instructions to get the job done? Also, where's a good source to buy the parts/seals that I will need?
If by special tools, you mean a 9/16" ratchet, then yes.
Seriously, I don't think a t-case could get much simpler short of being a 205. Depending on your mechanical aptitude, you probably won't need any instructions. I had planned on taking pictures for a walkthrough with mine, but it was so simple that I decided not to bother. My local truck & equipment shop said they could most likely special order the gaskets, but I ended up just using ultra gray RTV because the 203 will go to the dump very soon anyways. You can get the chains online, I'm guessing you can get the gaskets too. The output seals are the same as the 205s and should be easy to find. I've got 3 cases and all three sets of my seals/output bearings were in in great condition so I didn't bother replacing them.
The only advice I see anyone needing is how to handle the needle bearings. I hear all kinds of horror stories about them, but they're actually very easy to deal with. Pick up a tub of Assemblee Goo from NAPA. It's easier to work with and less messy than grease, and it turns this "huge headache" of a job into a 2-minute process. Once you pull off the aluminum tailcone with the speedo gear, you will see the differential on the main shaft. if you spin the shaft at all (it's kind of tempting), the needle bearings will slowly work their way off. Just use a container of some sort (like a red beer-pong cup) to catch them as they fall. You could take note of where the spacers are in between the needle bearings, but it's kind of a no-brainer anyway. I would recommend taking the whole thing apart and cleaning out the gearbox too. I had chunks of needle bearing in the magnet in there too. I can't help you on where to get more needle bearings. I grabbed a bunch out of the junkyard while I was getting some other parts. There are two sizes in there too, and I think about 150 total.
The output yokes have two different sized nuts on them. I don't remember the size, but I know I used my 3/4" drive sockets for them. They were like 1 3/8" and 1 5/16" or something.
I want to re-emphasize that Assemblee Goo stuff if you aren't already familiar with it. I use it a lot, and it makes those needle bearings so much easier to work with. Make sure you use non-detergent 30 wt., I think it's about 7-8 quarts. Oh, and there's shims on the output shaft under the tailcone. I know it is standard endplay (push/pull on the rear yoke with everything assembled), which I do by feel...I think it's like .005"-.012" but I wouldn't quote me on that since I've never done it by numbers.
If you get into trouble, post up pictures or shoot me a PM if you need to. I just did mine a couple months ago after not touching one for years so it's still pretty fresh in my mind.
