one of the better systems in use is the t-tech trans exchange system. you can ask shops around you what kind of flush/exhange they do.
the important part is to find out weather or not the system they use will use the vehicle's transmission pump (car would be on) or if they use an external pump.... external pump is the bad part.
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a note on antifreeze, in response to the rogue post about antifreeze
as for switching away from dexcool? no good reason to, at least not with the latest dexcool. early on in it's life (back in 95/96) there were some issues, but those have been corrected. the majority of the problems with it stem from someone or someplace putting the wrong kind of antifreeze in to top off the system, or using harsh tap water to mix. if you follow the instructions to use distilled water (or use the pre-mixed) and also follow the schedule for coolant replacement/flush, that should be plenty to keep your dexcool happy.