The autos are a 727 with an od on the back better known as a 518. These do not have a lock up converter so the trannys don't "break" often. But heat does tend to get out of hand do to loose converters that come in them from the factory and what most places will replace them with when they rebuild the tranny. Best bet is to replace the stock converter with a good tight low rpm engagment one from one of the big diesel trans guys or as I have done a Hughes for right at $400. It will make a very noticable difference in fuel mileage, throttle response, and most important keeping slip and temps low when towing.
I have 300,000 miles on my 92 W250 auto over 150,000 pushing 350hp and 850 tq hauling my slide in camper and towing trailers. Still get 20 mpg unloaded at every fill up. I keep the tranny fluid changed and watch my temps when it is hot in the hills. These trucks are pretty much bullet proof and easy to work on. There are so many ways to get more hp out of them on the cheap than you can imagine. Enjoy.
