The transmission behind the Cummins in my '93 d350 finally gave up. I had it rebuilt 150,000 mi prior, and the guy beefed it up with some modifications and Kevlar bands and red clutches or something like that. That 150,000 it was always heavily laden, towing the race trailer, or hauling the world's largest production truck camper, or both. So it did pretty good I think.
But now it needs to be freshened up. I have never rebuilt an automatic transmission before. I've done plenty of manual transmissions, engines, rear ends, etc. But the automatic always seems like a mysterious thing.

So should I try and tackle it myself? Where do I start, where do I get the parts, what parts do I get, how long will it take me to do it, do I need any special tools?

Thanks, Joel