Pro & Cons to changing old ATF fluid
 

I thought this YT clip was informative of "atf change basics" for those of us not too sure if and how to change your ATF along with an explanation of the differences between flushing,draining etc.

You Tube

Trans fluid pros and cons
 

Well, the 'old wives tales' of "dont change your fluid, you'll just have your tranny go out!" is actually true, to a point. If its 200,000+ miles and never been changed, yeah, it can cause a functioning trans to fail. However, these were high dollar ($60k in today's $) soccer mom cars, probably religiously serviced for the first 100k miles at least, and will go at least 300k miles before possibly wanting rebuild, so...

Change the fluid! Raise the hood, pull the grille, figure out which line on the trans cooler is the pressure line from the tranny and which is the return. Using a hose, put the pressure side into a bucket and put a hose onto the return side, connected to a reservoir of new fluid. Start the truck (or have a friend do it) and watch the output of fluid. Keep putting new fluid in as it runs out, until the output is clean and bright. Reconnect the line and drive away... after you verify your fluid level is up to snuff, of course!

Trans fluid pros and cons
 

If the output of fluid stops, have your friend shut it off immediately!