I'm just about to sit down and finish my thread on doing the re-seal, ala. Dave Petryk's excellent article. From what I've learned, and posted already, removing the box from the car is NOT A BIG JOB at all.
The worse part is getting the pitman arm off, which you'll need to do regardless. And that wasn't so bad at all, once I got the right puller.
The seal kit is under $20.00. The total time it took me to install all the O-rings and the 2 main shaft seals was about 4 hours. I did spend at least that much time reading the manual and Dave's article, and the thoughts of others here. I like to have done these jobs completely in my head before I even turn a wrench, but that's me.
Forget trying to do anything with the box on the car. Vegastech777's comment "Granted you will have to remove the gear box to seal it but you wont have to totally disassemble the box to the last peice." applies. But after you've got it out, just follow Petryk's procedure, which covers everything you'll need to know.
Tune in to my thread, I'm going to post up the results of doing the seal job....

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1986 560SL
2002 Toyota Camry
1993 Lexus