I have rebuilt a few transmisisons. The thing is, if you screw up just one little thing (and there are a lot of little things) your pulling it back out and completly tearing it back down again, and that's the good side, if you know what the problem is. So it better be 100% correct when assembled. Automatic are very unforgiving. Ive have lots of success rebuilding them, I ahve also had a couple of failures too, simple stupid mistakes on my part that went unoticed by me unitl it was to late. It can, and is fun. A great feeling of accomplishment, along with the agony of defeat if it wrong.
If you really want to do it, best bet is get as many books and liturature on the transmisison as possible, and study them, and have them handy during the rebuild. You have to be very clean and meticulous organized, and everthing must go back together the way it came out. IF a snap ring came out with the beveld side down upon removal, it better get put back in that way because IT MATTERS!!!!
Dean